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REPORTS > KEYWORD > LOWER BOUNDS:
Reports tagged with lower bounds:
TR94-027 | 12th December 1994
Stasys Jukna

#### A Note on Read-k Times Branching Programs

A syntactic read-k times branching program has the restriction
that no variable occurs more than k times on any path (whether or not
consistent). We exhibit an explicit Boolean function f which cannot
be computed by nondeterministic syntactic read-k times branching programs
of size less than exp(\sqrt{n}}k^{-2k}), ... more >>>

TR94-026 | 12th December 1994
Beate Bollig, Martin Sauerhoff, Detlef Sieling, Ingo Wegener

#### On the Power of Different Types of Restricted Branching Programs

Almost the same types of restricted branching programs (or
binary decision diagrams BDDs) are considered in complexity
theory and in applications like hardware verification. These
models are read-once branching programs (free BDDs) and certain
types of oblivious branching programs (ordered and indexed BDDs
with k layers). The complexity of ... more >>>

TR95-002 | 1st January 1995
Detlef Sieling

#### New Lower Bounds and Hierarchy Results for Restricted Branching Programs

In unrestricted branching programs all variables may be tested
arbitrarily often on each path. But exponential lower bounds are only
known, if on each path the number of tests of each variable is bounded
(Borodin, Razborov and Smolensky (1993)). We examine branching programs
in which for each path the ... more >>>

TR95-046 | 4th August 1995
Vince Grolmusz

#### On the Power of Circuits with Gates of Low L_1 Norms

We examine the power of Boolean functions with low L_1 norms in several
settings. In large part of the recent literature, the degree of a polynomial
which represents a Boolean function in some way was chosen to be the measure of the complexity of the Boolean function.
However, some functions ... more >>>

TR95-051 | 16th October 1995
Pascal Koiran

#### VC Dimension in Circuit Complexity

The main result of this paper is a Omega(n^{1/4}) lower bound
on the size of a sigmoidal circuit computing a specific AC^0_2 function.
This is the first lower bound for the computation model of sigmoidal
circuits with unbounded weights. We also give upper and lower bounds for
the ... more >>>

TR95-054 | 24th November 1995
Farid Ablayev, Marek Karpinski

#### On the Power of Randomized Branching Programs

We define the notion of a randomized branching program in
the natural way similar to the definition of a randomized
circuit. We exhibit an explicit function $f_{n}$ for which
we prove that:
1) $f_{n}$ can be computed by polynomial size randomized
... more >>>

TR95-063 | 19th December 1995
Dima Grigoriev, Marek Karpinski, Friedhelm Meyer auf der Heide, Roman Smolensky

#### A Lower Bound for Randomized Algebraic Decision Trees

We extend the lower bounds on the depth of algebraic decision trees
to the case of {\em randomized} algebraic decision trees (with
two-sided error) for languages being finite unions of hyperplanes
and the intersections of halfspaces, solving a long standing open
problem. As an application, among ... more >>>

TR96-026 | 25th March 1996
Stasys Jukna

#### Finite Limits and Monotone Computations

Revisions: 1 , Comments: 1

We prove a general combinatorial lower bound on the
size of monotone circuits. The argument is different from
Razborov's method of approximation, and is based on Sipser's
notion of finite limit' and Haken's counting bottlenecks' idea.
We then apply this criterion to the ... more >>>

TR96-031 | 30th April 1996

#### Networks of Spiking Neurons: The Third Generation of Neural Network Models

The computational power of formal models for
networks of spiking neurons is compared with
that of other neural network models based on
McCulloch Pitts neurons (i.e. threshold gates)
respectively sigmoidal gates. In particular it
is shown that networks of spiking neurons are
... more >>>

TR96-050 | 23rd September 1996
Petr Savicky, Stanislav Zak

#### A hierarchy for (1,+k)-branching programs with respect to k

Branching programs (b.p.'s) or decision diagrams are a general
graph-based model of sequential computation. The b.p.'s of
polynomial size are a nonuniform counterpart of LOG. Lower bounds
for different kinds of restricted b.p.'s are intensively
investigated. An important restriction are so called $k$-b.p.'s,
where each computation reads each input ... more >>>

TR96-052 | 2nd October 1996
Martin Dietzfelbinger

#### Gossiping and Broadcasting versus Computing Functions in Networks

The fundamental assumption in the classical theory of
dissemination of information in interconnection networks
(gossiping and broadcasting) is that atomic pieces of information
are communicated. We show that, under suitable assumptions about
the way processors may communicate, computing an n-ary function
that has a "critical input" (e.g., ... more >>>

TR97-007 | 21st February 1997
Stasys Jukna

#### Exponential Lower Bounds for Semantic Resolution

In a semantic resolution proof we operate with clauses only
but allow {\em arbitrary} rules of inference:

C_1 C_2 ... C_m
__________________
C

Consistency is the only requirement. We prove a very simple
exponential lower bound for the size ... more >>>

TR97-015 | 21st April 1997
Jan Krajicek

#### Interpolation by a game

We introduce a notion of a "real game"
(a generalization of the Karchmer - Wigderson game),
and "real communication complexity",
and relate them to the size of monotone real formulas
and circuits. We give an exponential lower bound
for tree-like monotone protocols of small real
communication complexity ... more >>>

TR97-019 | 5th May 1997
Martin Sauerhoff

#### A Lower Bound for Randomized Read-k-Times Branching Programs

In this paper, we are concerned with randomized OBDDs and randomized
read-k-times branching programs. We present an example of a Boolean
function which has polynomial size randomized OBDDs with small,
one-sided error, but only non-deterministic read-once branching
programs of exponential size. Furthermore, we discuss a lower bound
technique for randomized ... more >>>

TR97-020 | 15th May 1997
Oded Goldreich

#### A Sample of Samplers -- A Computational Perspective on Sampling (survey).

We consider the problem of estimating the average of a huge set of values.
That is,
given oracle access to an arbitrary function $f:\{0,1\}^n\mapsto[0,1]$,
we need to estimate $2^{-n} \sum_{x\in\{0,1\}^n} f(x)$
upto an additive error of $\epsilon$.
We are allowed to employ a randomized algorithm which may ... more >>>

TR97-030 | 25th August 1997
Martin Sauerhoff

#### On Nondeterminism versus Randomness for Read-Once Branching Programs

Randomized branching programs are a probabilistic model of computation
defined in analogy to the well-known probabilistic Turing machines.
In this paper, we present complexity theoretic results for randomized
read-once branching programs.
Our main result shows that nondeterminism can be more powerful than
randomness for read-once branching programs. We present a ... more >>>

TR97-042 | 22nd September 1997
Russell Impagliazzo, Pavel Pudlak, Jiri Sgall

#### Lower Bounds for the Polynomial Calculus and the Groebner Basis Algorithm

Razborov~\cite{Razborov96} recently proved that polynomial
calculus proofs of the pigeonhole principle $PHP_n^m$ must have
degree at least $\ceiling{n/2}+1$ over any field. We present a
simplified proof of the same result. The main
idea of our proof is the same as in the original proof
of Razborov: we want to describe ... more >>>

TR97-043 | 25th September 1997
Bruno Codenotti, Pavel Pudlak, Giovanni Resta

#### Some structural properties of low rank matrices related to computational complexity

Revisions: 1 , Comments: 1

We consider the conjecture stating that a matrix with rank
$o(n)$ and ones on the main diagonal must contain nonzero
entries on a $2\times 2$ submatrix with one entry on the main
diagonal. We show that a slightly stronger conjecture implies
that ... more >>>

TR97-050 | 27th October 1997
Stanislav Zak

#### A subexponential lower bound for branching programs restricted with regard to some semantic aspects

Branching programs (b.p.s) or binary decision diagrams are a
general graph-based model of sequential computation. The b.p.s of
polynomial size are a nonuniform counterpart of LOG. Lower bounds
for different kinds of restricted b.p.s are intensively
investigated. The restrictions based on the number of tests of
more >>>

TR98-002 | 8th January 1998
Jayram S. Thathachar

#### On Separating the Read-k-Times Branching Program Hierarchy

We obtain an exponential separation between consecutive
levels in the hierarchy of classes of functions computable by
polynomial-size syntactic read-$k$-times branching programs, for
{\em all\/} $k>0$, as conjectured by various
authors~\cite{weg87,ss93,pon95b}. For every $k$, we exhibit two
explicit functions that can be computed by linear-sized
read-$(\kpluso)$-times branching programs but ... more >>>

TR98-004 | 13th January 1998
Farid Ablayev, Marek Karpinski

#### On the Power of Randomized Ordered Branching Programs

We introduce a model of a {\em randomized branching program}
in a natural way similar to the definition of a randomized circuit.
We exhibit an explicit boolean function
$f_{n}:\{0,1\}^{n}\to\{0,1\}$ for which we prove that:

1) $f_{n}$ can be computed by a polynomial size randomized
... more >>>

TR98-011 | 29th January 1998
Farid Ablayev, Marek Karpinski

#### A Lower Bound for Integer Multiplication on Randomized Read-Once Branching Programs

We prove an exponential lower bound ($2^{\Omega(n/\log n)}$) on the
size of any randomized ordered read-once branching program
computing integer multiplication. Our proof depends on proving
a new lower bound on Yao's randomized one-way communication
complexity of certain boolean functions. It generalizes to some
other ... more >>>

TR98-018 | 27th March 1998
Martin Sauerhoff

#### Randomness and Nondeterminism are Incomparable for Read-Once Branching Programs

Comments: 1

We extend the tools for proving lower bounds for randomized branching
programs by presenting a new technique for the read-once case which is
applicable to a large class of functions. This technique fills the gap
between simple methods only applicable for OBDDs and the well-known
"rectangle technique" of Borodin, Razborov ... more >>>

TR98-028 | 28th May 1998
Paul Beame, Faith Fich

#### On Searching Sorted Lists: A Near-Optimal Lower Bound

We obtain improved lower bounds for a class of static and dynamic
data structure problems that includes several problems of searching
sorted lists as special cases.

These lower bounds nearly match the upper bounds given by recent
striking improvements in searching algorithms given by Fredman and
Willard's ... more >>>

TR98-030 | 9th June 1998
Stasys Jukna, Stanislav Zak

#### On Branching Programs With Bounded Uncertainty

We propose an information-theoretic approach to proving
lower bounds on the size of branching programs (b.p.). The argument
is based on Kraft-McMillan type inequalities for the average amount of
uncertainty about (or entropy of) a given input during various
stages of the computation. ... more >>>

TR98-038 | 9th July 1998
Marek Karpinski

#### On the Computational Power of Randomized Branching Programs

We survey some upper and lower bounds established recently on
the sizes of randomized branching programs computing explicit
boolean functions. In particular, we display boolean
functions on which randomized read-once ordered branching
programs are exponentially more powerful than deterministic
or nondeterministic read-$k$-times branching programs for ... more >>>

TR98-041 | 27th July 1998
Stasys Jukna

#### Combinatorics of Monotone Computations

We consider a general model of monotone circuits, which
we call d-local. In these circuits we allow as gates:
(i) arbitrary monotone Boolean functions whose minterms or
maxterms (or both) have length at most <i>d</i>, and
(ii) arbitrary real-valued non-decreasing functions on ... more >>>

TR98-045 | 17th July 1998
Detlef Sieling

#### A Separation of Syntactic and Nonsyntactic (1,+k)-Branching Programs

For (1,+k)-branching programs and read-k-times branching
programs syntactic and nonsyntactic variants can be distinguished. The
nonsyntactic variants correspond in a natural way to sequential
computations with restrictions on reading the input while lower bound
proofs are easier or only known for the syntactic variants. In this
paper it is shown ... more >>>

TR98-050 | 6th July 1998
Farid Ablayev, Svetlana Ablayeva

#### A Discrete Approximation and Communication Complexity Approach to the Superposition Problem

The superposition (or composition) problem is a problem of
representation of a function $f$ by a superposition of "simpler" (in a
different meanings) set $\Omega$ of functions. In terms of circuits
theory this means a possibility of computing $f$ by a finite circuit
with 1 fan-out gates $\Omega$ of functions. ... more >>>

TR98-053 | 30th August 1998
Paul Beame, Michael Saks, Jayram S. Thathachar

#### Time-Space Tradeoffs for Branching Programs

Comments: 1

We obtain the first non-trivial time-space tradeoff lower bound for
functions f:{0,1}^n ->{0,1} on general branching programs by exhibiting a
Boolean function f that requires exponential size to be computed by any
branching program of length cn, for some constant c>1. We also give the first
separation result between the ... more >>>

TR99-019 | 7th June 1999
Detlef Sieling

#### Lower Bounds for Linear Transformed OBDDs and FBDDs

Linear Transformed Ordered Binary Decision Diagrams (LTOBDDs) have
been suggested as a generalization of OBDDs for the representation and
manipulation of Boolean functions. Instead of variables as in the
case of OBDDs parities of variables may be tested at the nodes of an
LTOBDD. By this extension it is ... more >>>

TR99-020 | 9th June 1999
Marek Karpinski

#### Randomized Complexity of Linear Arrangements and Polyhedra

We survey some of the recent results on the complexity of recognizing
n-dimensional linear arrangements and convex polyhedra by randomized
algebraic decision trees. We give also a number of concrete applications
of these results. In particular, we derive first nontrivial, in fact
quadratic, ... more >>>

TR99-044 | 30th September 1999
Farid Ablayev

#### On Complexity of Regular $(1,+k)$-Branching Programs

A regular $(1,+k)$-branching program ($(1,+k)$-ReBP) is an
ordinary branching program with the following restrictions: (i)
along every consistent path at most $k$ variables are tested more
than once, (ii) for each node $v$ on all paths from the source to
$v$ the same set $X(v)\subseteq X$ of variables is ... more >>>

TR99-048 | 7th December 1999
Beate Bollig, Ingo Wegener

#### Asymptotically Optimal Bounds for OBDDs and the Solution of Some Basic OBDD Problems

Ordered binary decision diagrams (OBDDs) are nowadays the
most common dynamic data structure or representation type
for Boolean functions. Among the many areas of application
are verification, model checking, and computer aided design.
For many functions it is easy to estimate the OBDD ... more >>>

TR00-001 | 14th January 2000
Piotr Berman, Moses Charikar, Marek Karpinski

#### On-Line Load Balancing for Related Machines

We consider the problem of scheduling permanent jobs on related machines
in an on-line fashion. We design a new algorithm that achieves the
competitive ratio of $3+\sqrt{8}\approx 5.828$ for the deterministic
version, and $3.31/\ln 2.155 \approx 4.311$ for its randomized variant,
improving the previous competitive ratios ... more >>>

TR00-025 | 20th May 2000
Paul Beame, Michael Saks, Xiaodong Sun, Erik Vee

#### Super-linear time-space tradeoff lower bounds for randomized computation

We prove the first time-space lower bound tradeoffs for randomized
computation of decision problems. The bounds hold even in the
case that the computation is allowed to have arbitrary probability
of error on a small fraction of inputs. Our techniques are an
extension of those used by Ajtai in his ... more >>>

TR00-029 | 30th April 2000
Ran Raz, Amir Shpilka

#### Lower Bounds for Matrix Product, in Bounded Depth Circuits with Arbitrary Gates

Revisions: 1

We prove super-linear lower bounds for the number of edges
in constant depth circuits with $n$ inputs and up to $n$ outputs.
Our lower bounds are proved for all types of constant depth
circuits, e.g., constant depth arithmetic circuits, constant depth
threshold circuits ... more >>>

TR00-030 | 31st May 2000

#### A Simple Model for Neural Computation with Firing Rates and Firing Correlations

A simple extension of standard neural network models is introduced that
provides a model for neural computations that involve both firing rates and
firing correlations. Such extension appears to be useful since it has been
shown that firing correlations play a significant computational role in
many biological neural systems. Standard ... more >>>

TR00-032 | 31st May 2000

#### On the Computational Power of Winner-Take-All

In this paper the computational power of a new type of gate is studied:
winner-take-all gates. This work is motivated by the fact that the cost
of implementing a winner-take-all gate in analog VLSI is about the same
as that of implementing a threshold gate.

We show that ... more >>>

TR00-042 | 21st June 2000
Lars Engebretsen

#### Lower Bounds for non-Boolean Constraint Satisfaction

Revisions: 1

We show that the k-CSP problem over a finite Abelian group G
cannot be approximated within |G|^{k-O(sqrt{k})}-epsilon, for
any constant epsilon>0, unless P=NP. This lower bound matches
well with the best known upper bound, |G|^{k-1}, of Serna,
Trevisan and Xhafa. The proof uses a combination of PCP
techniques---most notably a ... more >>>

TR00-057 | 25th July 2000
Martin Sauerhoff

#### An Improved Hierarchy Result for Partitioned BDDs

One of the great challenges of complexity theory is the problem of
analyzing the dependence of the complexity of Boolean functions on the
resources nondeterminism and randomness. So far, this problem could be
solved only for very few models of computation. For so-called
partitioned binary decision diagrams, which are a ... more >>>

TR00-058 | 1st August 2000
Martin Sauerhoff

#### Approximation of Boolean Functions by Combinatorial Rectangles

This paper deals with the number of monochromatic combinatorial
rectangles required to approximate a Boolean function on a constant
fraction of all inputs, where each rectangle may be defined with
respect to its own partition of the input variables. The main result
of the paper is that the number of ... more >>>

TR00-089 | 1st December 2000
Lars Engebretsen, Marek Karpinski

#### Approximation Hardness of TSP with Bounded Metrics

Revisions: 1

The general asymmetric (and metric) TSP is known to be approximable
only to within an O(log n) factor, and is also known to be
approximable within a constant factor as soon as the metric is
bounded. In this paper we study the asymmetric and symmetric TSP
problems with bounded metrics ... more >>>

TR00-091 | 21st December 2000
Cristina Bazgan, Wenceslas Fernandez de la Vega, Marek Karpinski

#### Approximability of Dense Instances of NEAREST CODEWORD Problem

We give a polynomial time approximation scheme (PTAS) for dense
instances of the NEAREST CODEWORD problem.

more >>>

TR01-025 | 28th March 2001
Piotr Berman, Marek Karpinski

#### Approximating Minimum Unsatisfiability of Linear Equations

We consider the following optimization problem:
given a system of m linear equations in n variables over a certain field,
a feasible solution is any assignment of values to the variables, and the
minimized objective function is the number of equations that are not
satisfied. For ... more >>>

TR01-026 | 3rd April 2001
Piotr Berman, Marek Karpinski

#### Approximation Hardness of Bounded Degree MIN-CSP and MIN-BISECTION

We consider bounded occurrence (degree) instances of a minimum
constraint satisfaction problem MIN-LIN2 and a MIN-BISECTION problem for
graphs. MIN-LIN2 is an optimization problem for a given system of linear
equations mod 2 to construct a solution that satisfies the minimum number
of them. E3-OCC-MIN-E3-LIN2 ... more >>>

TR01-034 | 30th April 2001
Cristina Bazgan, Wenceslas Fernandez de la Vega, Marek Karpinski

#### Polynomial Time Approximation Schemes for Dense Instances of Minimum Constraint Satisfaction

It is known that large fragments of the class of dense
Minimum Constraint Satisfaction (MIN-CSP) problems do not have
polynomial time approximation schemes (PTASs) contrary to their
Maximum Constraint Satisfaction analogs. In this paper we prove,
somewhat surprisingly, that the minimum satisfaction of dense
instances of kSAT-formulas, ... more >>>

TR01-039 | 18th May 2001
Stasys Jukna, Stanislav Zak

#### On Uncertainty versus Size in Branching Programs

Revisions: 1

We propose an information-theoretic approach to proving lower
bounds on the size of branching programs. The argument is based on
Kraft-McMillan type inequalities for the average amount of
uncertainty about (or entropy of) a given input during the various
stages of computation. The uncertainty is measured by the average
more >>>

TR01-041 | 23rd May 2001
Eric Allender, Michal Koucky, Detlef Ronneburger, Sambuddha Roy, V Vinay

#### Time-Space Tradeoffs in the Counting Hierarchy

We extend the lower bound techniques of [Fortnow], to the
unbounded-error probabilistic model. A key step in the argument
is a generalization of Nepomnjascii's theorem from the Boolean
setting to the arithmetic setting. This generalization is made
possible, due to the recent discovery of logspace-uniform TC^0
more >>>

TR01-042 | 31st May 2001
Marek Karpinski

#### Approximating Bounded Degree Instances of NP-Hard Problems

We present some of the recent results on computational complexity
of approximating bounded degree combinatorial optimization problems. In
particular, we present the best up to now known explicit nonapproximability
bounds on the very small degree optimization problems which are of
particular importance on the intermediate stages ... more >>>

TR01-049 | 11th July 2001
Stasys Jukna, Georg Schnitger

#### On Multi-Partition Communication Complexity of Triangle-Freeness

Comments: 2

We show that recognizing the $K_3$-freeness and $K_4$-freeness of
graphs is hard, respectively, for two-player nondeterministic
communication protocols with exponentially many partitions and for
nondeterministic (syntactic) read-$s$ times branching programs.

The key ingradient is a generalization of a coloring lemma, due to
Papadimitriou and Sipser, which says that for every ... more >>>

TR01-053 | 17th July 2001
Piotr Berman, Marek Karpinski

#### Efficient Amplifiers and Bounded Degree Optimization

This paper studies the existence of efficient (small size)
amplifiers for proving explicit inaproximability results for bounded degree
and bounded occurrence combinatorial optimization problems, and gives
an explicit construction for such amplifiers. We use this construction
also later to improve the currently best known approximation lower bounds
more >>>

TR01-060 | 23rd August 2001
Amir Shpilka

#### Lower bounds for matrix product

We prove lower bounds on the number of product gates in bilinear
and quadratic circuits that
compute the product of two $n \times n$ matrices over finite fields.
In particular we obtain the following results:

1. We show that the number of product gates in any bilinear
(or quadratic) ... more >>>

TR01-066 | 28th September 2001
Pavol Duris, Juraj Hromkovic, Stasys Jukna, Martin Sauerhoff, Georg Schnitger

#### On Multipartition Communication Complexity

We study k-partition communication protocols, an extension
of the standard two-party best-partition model to k input partitions.
The main results are as follows.

1. A strong explicit hierarchy on the degree of
non-obliviousness is established by proving that,
using k+1 partitions instead of k may decrease
the communication complexity from ... more >>>

TR01-067 | 18th September 2001
Hubie Chen

#### Polynomial Programs and the Razborov-Smolensky Method

Representations of boolean functions as polynomials (over rings) have
been used to establish lower bounds in complexity theory. Such
representations were used to great effect by Smolensky, who
established that MOD q \notin AC^0[MOD p] (for distinct primes p, q)
by representing AC^0[MOD p] functions as low-degree multilinear
polynomials over ... more >>>

TR01-073 | 24th October 2001
Beate Bollig, Philipp Woelfel, Stephan Waack

#### Parity Graph-driven Read-Once Branching Programs and an Exponential Lower Bound for Integer Multiplication

Revisions: 1

Branching programs are a well-established computation model
for Boolean functions, especially read-once branching programs
have been studied intensively. Exponential lower bounds for
deterministic and nondeterministic read-once branching programs
are known for a long time. On the other hand, the problem of
proving superpolynomial lower bounds ... more >>>

TR01-095 | 12th November 2001
Hubie Chen

#### Arithmetic Versions of Constant Depth Circuit Complexity Classes

The boolean circuit complexity classes
AC^0 \subseteq AC^0[m] \subseteq TC^0 \subseteq NC^1 have been studied
intensely. Other than NC^1, they are defined by constant-depth
circuits of polynomial size and unbounded fan-in over some set of
allowed gates. One reason for interest in these classes is that they
contain the ... more >>>

TR01-100 | 14th December 2001
Noga Alon, Wenceslas Fernandez de la Vega, Ravi Kannan, Marek Karpinski

#### Random Sampling and Approximation of MAX-CSP Problems

We present a new efficient sampling method for approximating
r-dimensional Maximum Constraint Satisfaction Problems, MAX-rCSP, on
n variables up to an additive error \epsilon n^r.We prove a new
general paradigm in that it suffices, for a given set of constraints,
to pick a small uniformly random ... more >>>

TR01-101 | 14th December 2001
Philipp Woelfel

#### A Lower Bound Technique for Restricted Branching Programs and Applications

We present a new lower bound technique for two types of restricted
Branching Programs (BPs), namely for read-once BPs (BP1s) with
restricted amount of nondeterminism and for (1,+k)-BPs. For this
technique, we introduce the notion of (strictly) k-wise l-mixed
Boolean functions, which generalizes the concept of l-mixedness ... more >>>

TR02-012 | 3rd February 2002
Ran Raz

#### On the Complexity of Matrix Product

We prove a lower bound of $\Omega(m^2 \log m)$ for the size of
any arithmetic circuit for the product of two matrices,
over the real or complex numbers, as long as the circuit doesn't
use products with field elements of absolute value larger than 1
(where $m \times m$ is ... more >>>

TR02-013 | 30th January 2002
Chris Pollett, Farid Ablayev, Cristopher Moore, Chris Pollett

#### Quantum and Stochastic Programs of Bounded Width

Revisions: 1

We prove upper and lower bounds on the power of quantum and stochastic
branching programs of bounded width. We show any NC^1 language can
be accepted exactly by a width-2 quantum branching program of
polynomial length, in contrast to the classical case where width 5 is
necessary unless \NC^1=\ACC. ... more >>>

TR02-033 | 11th June 2002
Beate Bollig

#### A very simple function that requires exponential size nondeterministic graph-driven read-once branching programs

Branching programs are a well-established computation
model for boolean functions, especially read-once
branching programs (BP1s) have been studied intensively.
A very simple function $f$ in $n^2$ variables is
exhibited such that both the function $f$ and its negation
$\neg f$ can be computed by $\Sigma^3_p$-circuits,
the ... more >>>

TR02-059 | 9th August 2002
Iordanis Kerenidis, Ronald de Wolf

#### Exponential Lower Bound for 2-Query Locally Decodable Codes

We prove exponential lower bounds on the length of 2-query
locally decodable codes. Goldreich et al. recently proved such bounds
for the special case of linear locally decodable codes.
Our proof shows that a 2-query locally decodable code can be decoded
with only 1 quantum query, and then ... more >>>

TR02-064 | 14th November 2002
Andrej Bogdanov, Luca Trevisan

#### Lower Bounds for Testing Bipartiteness in Dense Graphs

We consider the problem of testing bipartiteness in the adjacency
matrix model. The best known algorithm, due to Alon and Krivelevich,
distinguishes between bipartite graphs and graphs that are
$\epsilon$-far from bipartite using $O((1/\epsilon^2)polylog(1/epsilon)$
queries. We show that this is optimal for non-adaptive algorithms,
up to the ... more >>>

TR02-072 | 12th November 2002
Scott Aaronson

#### Quantum Lower Bound for Recursive Fourier Sampling

We revisit the oft-neglected 'recursive Fourier sampling' (RFS) problem, introduced by Bernstein and Vazirani to prove an oracle separation between BPP and BQP. We show that the known quantum algorithm for RFS is essentially optimal, despite its seemingly wasteful need to uncompute information. This implies that, to place BQP outside ... more >>>

TR03-008 | 11th February 2003
Piotr Berman, Marek Karpinski

#### Improved Approximation Lower Bounds on Small Occurrence Optimization

We improve a number of approximation lower bounds for
bounded occurrence optimization problems like MAX-2SAT,
E2-LIN-2, Maximum Independent Set and Maximum-3D-Matching.

more >>>

TR03-022 | 11th April 2003
Piotr Berman, Marek Karpinski, Alexander D. Scott

#### Approximation Hardness and Satisfiability of Bounded Occurrence Instances of SAT

We study approximation hardness and satisfiability of bounded
occurrence uniform instances of SAT. Among other things, we prove
the inapproximability for SAT instances in which every clause has
exactly 3 literals and each variable occurs exactly 4 times,
and display an explicit ... more >>>

TR03-037 | 30th April 2003
Ziv Bar-Yossef

#### Sampling Lower Bounds via Information Theory

We present a novel technique, based on the Jensen-Shannon divergence
from information theory, to prove lower bounds on the query complexity
of sampling algorithms that approximate functions over arbitrary
domain and range. Unlike previous methods, our technique does not
use a reduction from a binary decision problem, but rather ... more >>>

TR03-065 | 19th June 2003
Wee, Hoeteck

#### Compressibility Lower Bounds in Oracle Settings

A source is compressible if we can efficiently compute short
descriptions of strings in the support and efficiently
recover the strings from the descriptions. In this paper, we
present a technique for proving lower bounds on
compressibility in an oracle setting, which yields the
following results:

- We ... more >>>

TR03-067 | 14th August 2003
Ran Raz

#### Multi-Linear Formulas for Permanent and Determinant are of Super-Polynomial Size

An arithmetic formula is multi-linear if the polynomial computed
by each of its sub-formulas is multi-linear. We prove that any
multi-linear arithmetic formula for the permanent or the
determinant of an $n \times n$ matrix is of size super-polynomial
in $n$.

more >>>

TR03-068 | 30th July 2003
Matthias Homeister

#### Lower Bounds for the Sum of Graph--driven Read--Once Parity Branching Programs

We prove the first lower bound for restricted read-once parity branching
programs with unlimited parity nondeterminism where for each input the
variables may be tested according to several orderings.

Proving a superpolynomial lower bound for read-once parity branching
programs is still a challenging open problem. The following variant ... more >>>

TR03-070 | 19th August 2003
Amit Chakrabarti, Oded Regev

#### An Optimal Randomised Cell Probe Lower Bound for Approximate Nearest Neighbour Searching

We consider the approximate nearest neighbour search problem on the
Hamming Cube $\b^d$. We show that a randomised cell probe algorithm that
uses polynomial storage and word size $d^{O(1)}$ requires a worst case
query time of $\Omega(\log\log d/\log\log\log d)$. The approximation
factor may be as loose as $2^{\log^{1-\eta}d}$ for any ... more >>>

TR03-087 | 10th December 2003
Richard Beigel, Lance Fortnow, William Gasarch

#### A Nearly Tight Bound for Private Information Retrieval Protocols

Comments: 1

We show that any 1-round 2-server Private Information
Retrieval Protocol where the answers are 1-bit long must ask questions
that are at least $n-2$ bits long, which is nearly equal to the known
$n-1$ upper bound. This improves upon the approximately $0.25n$ lower
bound of Kerenidis and de Wolf while ... more >>>

TR04-003 | 22nd December 2003
Pascal Koiran

#### Valiant's model and the cost of computing integers

Let $\tau(k)$ be the minimum number of arithmetic operations
required to build the integer $k \in \N$ from the constant 1.
A sequence $x_k$ is said to be easy to compute'' if
there exists a polynomial $p$ such that $\tau(x_k) \leq p(\log k)$
for all $k \geq ... more >>> TR04-004 | 13th January 2004 Ramamohan Paturi, Pavel Pudlak #### Circuit lower bounds and linear codes In 1977 Valiant proposed a graph theoretical method for proving lower bounds on algebraic circuits with gates computing linear functions. He used this method to reduce the problem of proving lower bounds on circuits with linear gates to to proving lower bounds on the rigidity of a matrix, a ... more >>> TR04-041 | 18th May 2004 Michael Alekhnovich, Edward Hirsch, Dmitry Itsykson #### Exponential lower bounds for the running time of DPLL algorithms on satisfiable formulas DPLL (for Davis, Putnam, Logemann, and Loveland) algorithms form the largest family of contemporary algorithms for SAT (the propositional satisfiability problem) and are widely used in applications. The recursion trees of DPLL algorithm executions on unsatisfiable formulas are equivalent to tree-like resolution proofs. Therefore, lower bounds for tree-like resolution (which ... more >>> TR04-042 | 21st May 2004 Ran Raz #### Multilinear-$NC_1\ne$Multilinear-$NC_2$An arithmetic circuit or formula is multilinear if the polynomial computed at each of its wires is multilinear. We give an explicit example for a polynomial$f(x_1,...,x_n)$, with coefficients in$\{0,1\}$, such that over any field: 1)$f$can be computed by a polynomial-size multilinear circuit of depth$O(\log^2 ... more >>>

TR04-085 | 3rd October 2004
Erez Petrank, Guy Rothblum

#### Selection from Structured Data Sets

A large body of work studies the complexity of selecting the
$j$-th largest element in an arbitrary set of $n$ elements (a.k.a.
the select$(j)$ operation). In this work, we study the
complexity of select in data that is partially structured by
an initial preprocessing stage and in a data structure ... more >>>

TR05-021 | 14th February 2005
Stasys Jukna

#### Disproving the single level conjecture

Revisions: 2 , Comments: 1

We consider the minimal number of AND and OR gates in monotone
circuits for quadratic boolean functions, i.e. disjunctions of
length-$2$ monomials. The single level conjecture claims that
monotone single level circuits, i.e. circuits which have only one
level of AND gates, for quadratic functions ... more >>>

TR05-103 | 17th August 2005
Leonid Gurvits

#### A proof of hyperbolic van der Waerden conjecture : the right generalization is the ultimate simplification

Consider a homogeneous polynomial $p(z_1,...,z_n)$ of degree $n$ in $n$ complex variables .
Assume that this polynomial satisfies the property : \\

$|p(z_1,...,z_n)| \geq \prod_{1 \leq i \leq n} Re(z_i)$ on the domain $\{(z_1,...,z_n) : Re(z_i) \geq 0 , 1 \leq i \leq n \}$ . \\

We prove that ... more >>>

TR05-136 | 14th November 2005
Anna Gal, Michal Koucky, Pierre McKenzie

#### Incremental branching programs

In this paper we propose the study of a new model of restricted
branching programs which we call incremental branching programs.
This is in line with the program proposed by Cook in 1974 as an
approach for separating the class of problems solvable in logarithmic
space from problems solvable ... more >>>

TR06-060 | 4th May 2006
Ran Raz, Amir Shpilka, Amir Yehudayoff

#### A Lower Bound for the Size of Syntactically Multilinear Arithmetic Circuits

We construct an explicit polynomial $f(x_1,...,x_n)$, with
coefficients in ${0,1}$, such that the size of any syntactically
multilinear arithmetic circuit computing $f$ is at least
$\Omega( n^{4/3} / log^2(n) )$. The lower bound holds over any field.

more >>>

TR06-102 | 15th August 2006
Luis Rademacher, Santosh Vempala

#### Dispersion of Mass and the Complexity of Randomized Geometric Algorithms

How much can randomness help computation? Motivated by this general question and by volume computation, one of the few instances where randomness provably helps, we analyze a notion of dispersion and connect it to asymptotic convex geometry. We obtain a nearly quadratic lower bound on the complexity of randomized volume ... more >>>

TR07-009 | 8th January 2007
Nathan Segerlind

#### Nearly-Exponential Size Lower Bounds for Symbolic Quantifier Elimination Algorithms and OBDD-Based Proofs of Unsatisfiability

Revisions: 1 , Comments: 1

We demonstrate a family of propositional formulas in conjunctive normal form
so that a formula of size $N$ requires size $2^{\Omega(\sqrt[7]{N/logN})}$
to refute using the tree-like OBDD refutation system of
Atserias, Kolaitis and Vardi
with respect to all variable orderings.
All known symbolic quantifier elimination algorithms for satisfiability
generate ... more >>>

TR07-036 | 6th April 2007
Ryan Williams

#### Time-Space Tradeoffs for Counting NP Solutions Modulo Integers

We prove the first time-space tradeoffs for counting the number of solutions to an NP problem modulo small integers, and also improve upon the known time-space tradeoffs for Sat. Let m be a positive integer, and define MODm-Sat to be the problem of determining if a given Boolean formula has ... more >>>

TR07-038 | 23rd April 2007
Iftach Haitner, Jonathan J. Hoch, Omer Reingold, Gil Segev

#### Finding Collisions in Interactive Protocols -- A Tight Lower Bound on the Round Complexity of Statistically-Hiding Commitments

We study the round complexity of various cryptographic protocols. Our main result is a tight lower bound on the round complexity of any fully-black-box construction of a statistically-hiding commitment scheme from one-way permutations, and even from trapdoor permutations. This lower bound matches the round complexity of the statistically-hiding commitment scheme ... more >>>

TR07-049 | 1st June 2007
Beate Bollig, Niko Range, Ingo Wegener

#### Exact OBDD Bounds for some Fundamental Functions

Ordered binary decision diagrams (OBDDs) are nowadays the most common
dynamic data structure or representation type for Boolean functions.
Among the many areas of application are verification, model checking,
computer aided design, relational algebra, and symbolic graph algorithms.
Although many even exponential lower bounds on the OBDD size of Boolean ... more >>>

TR07-077 | 7th August 2007
Ilias Diakonikolas, Homin Lee, Kevin Matulef, Krzysztof Onak, Ronitt Rubinfeld, Rocco Servedio, Andrew Wan

#### Testing for Concise Representations

We describe a general method for testing whether a function on n input variables has a concise representation. The approach combines ideas from the junta test of Fischer et al. with ideas from learning theory, and yields property testers that make poly(s/epsilon) queries (independent of n) for Boolean function classes ... more >>>

TR07-085 | 2nd September 2007
Ran Raz, Amir Yehudayoff

#### Multilinear Formulas, Maximal-Partition Discrepancy and Mixed-Sources Extractors

We study multilinear formulas, monotone arithmetic circuits, maximal-partition discrepancy, best-partition communication complexity and extractors constructions. We start by proving lower bounds for an explicit polynomial for the following three subclasses of syntactically multilinear arithmetic formulas over the field C and the set of variables {x1,...,xn}:

1. Noise-resistant. A syntactically multilinear ... more >>>

TR07-090 | 11th September 2007
Shachar Lovett

#### Tight lower bounds for adaptive linearity tests

Revisions: 1 , Comments: 1

Linearity tests are randomized algorithms which have oracle access to the truth table of some function $f$,
which are supposed to distinguish between linear functions and functions which are far from linear. Linearity tests were first introduced by Blum, Luby and Rubenfeld in \cite{BLR93}, and were later used in the ... more >>>

TR07-099 | 30th September 2007
Dieter van Melkebeek

#### A Survey of Lower Bounds for Satisfiability and Related Problems

Ever since the fundamental work of Cook from 1971, satisfiability has been recognized as a central problem in computational complexity. It is widely believed to be intractable, and yet till recently even a linear-time, logarithmic-space algorithm for satisfiability was not ruled out. In 1997 Fortnow, building on earlier work by ... more >>>

TR07-110 | 24th October 2007
Beate Bollig

#### The Optimal Read-Once Branching Program Complexity for the Direct Storage Access Function

Branching programs are computation models
measuring the space of (Turing machine) computations.
Read-once branching programs (BP1s) are the
most general model where each graph-theoretical path is the computation
path for some input. Exponential lower bounds on the size of read-once
branching programs are known since a long time. Nevertheless, there ... more >>>

TR07-121 | 21st November 2007
Zeev Dvir, Amir Shpilka, Amir Yehudayoff

#### Hardness-Randomness Tradeoffs for Bounded Depth Arithmetic Circuits

In this paper we show that lower bounds for bounded depth arithmetic circuits imply derandomization of polynomial identity testing for bounded depth arithmetic circuits. More formally, if there exists an explicit polynomial f(x_1,...,x_m) that cannot be computed by a depth d arithmetic circuit of small size then there exists ... more >>>

TR07-124 | 23rd November 2007
Nitin Saxena

#### Diagonal Circuit Identity Testing and Lower Bounds

In this paper we give the first deterministic polynomial time algorithm for testing whether a {\em diagonal} depth-$3$ circuit $C(\arg{x}{n})$ (i.e. $C$ is a sum of powers of linear functions) is zero. We also prove an exponential lower bound showing that such a circuit will compute determinant or permanent only ... more >>>

TR08-001 | 5th January 2008
Ran Raz

#### Elusive Functions and Lower Bounds for Arithmetic Circuits

A basic fact in linear algebra is that the image of the curve
$f(x)=(x^1,x^2,x^3,...,x^m)$, say over $C$, is not contained in any
$m-1$ dimensional affine subspace of $C^m$. In other words, the image
of $f$ is not contained in the image of any polynomial-mapping
$G:C^{m-1} ---> C^m$ ... more >>>

TR08-006 | 18th January 2008
Ran Raz, Amir Yehudayoff

#### Lower Bounds and Separations for Constant Depth Multilinear Circuits

We prove an exponential lower bound for the size of constant depth multilinear arithmetic circuits computing either the determinant or the permanent (a circuit is called multilinear, if the polynomial computed by each of its gates is multilinear). We also prove a super-polynomial separation between the size of product-depth $d$ ... more >>>

TR08-024 | 26th February 2008
Paul Beame, Trinh Huynh

#### On the Value of Multiple Read/Write Streams for Approximating Frequency Moments

Revisions: 2

Recently, an extension of the standard data stream model has been introduced in which an algorithm can create and manipulate multiple read/write streams in addition to its input data stream. Like the data stream model, the most important parameter for this model is the amount of internal memory used by ... more >>>

TR08-038 | 4th April 2008
Eric Allender, Michal Koucky

#### Amplifying Lower Bounds by Means of Self-Reducibility

Revisions: 2

We observe that many important computational problems in NC^1 share a simple self-reducibility property. We then show that, for any problem A having this self-reducibility property, A has polynomial size TC^0 circuits if and only if it has TC^0 circuits of size n^{1+\epsilon} for every \epsilon > 0 (counting the ... more >>>

TR08-056 | 22nd April 2008
Beate Bollig

#### On the OBDD complexity of the most significant bit of integer multiplication

Integer multiplication as one of the basic arithmetic functions has been
in the focus of several complexity theoretical investigations.
Ordered binary decision diagrams (OBDDs) are one of the most common
dynamic data structures for boolean functions.
Among the many areas of application are verification, model checking,
computer-aided design, relational algebra, ... more >>>

TR08-057 | 14th May 2008
Alexander A. Sherstov

#### Communication Lower Bounds Using Dual Polynomials

Representations of Boolean functions by real polynomials
play an important role in complexity theory. Typically,
one is interested in the least degree of a polynomial
p(x_1,...,x_n) that approximates or sign-represents
a given Boolean function f(x_1,...,x_n). This article
surveys a new and growing body of work in communication
complexity that centers ... more >>>

TR08-061 | 11th June 2008
Paul Beame, Trinh Huynh

#### Multiparty Communication Complexity of AC^0

Revisions: 1

We prove n^Omega(1) lower bounds on the multiparty communication complexity of AC^0 functions in the number-on-forehead (NOF) model for up to Theta(log n) players. These are the first lower bounds for any AC^0 function for omega(loglog n) players. In particular we show that there are families of depth 3 read-once ... more >>>

TR08-062 | 11th June 2008
Manindra Agrawal, V Vinay

#### Arithmetic Circuits: A Chasm at Depth Four

We show that proving exponential lower bounds on depth four arithmetic
circuits imply exponential lower bounds for unrestricted depth arithmetic
circuits. In other words, for exponential sized circuits additional depth
beyond four does not help.

We then show that a complete black-box derandomization of Identity Testing problem for depth four ... more >>>

TR08-082 | 11th September 2008
Paul Beame, Trinh Huynh

#### Multiparty Communication Complexity and Threshold Circuit Size of AC^0

Revisions: 2

We prove an n^{Omega(1)}/2^{O(k)} lower bound on the randomized k-party communication complexity of read-once depth 4 AC^0 functions in the number-on-forehead (NOF) model for O(log n) players. These are the first non-trivial lower bounds for general NOF multiparty communication complexity for any AC^0 function for omega(log log n) players. For ... more >>>

TR09-013 | 4th February 2009
Atri Rudra

#### Limits to List Decoding Random Codes

It has been known since [Zyablov and Pinsker 1982] that a random $q$-ary code of rate $1-H_q(\rho)-\eps$ (where $0<\rho<1-1/q$, $\eps>0$ and $H_q(\cdot)$ is the $q$-ary entropy function) with high probability is a $(\rho,1/\eps)$-list decodable code. (That is, every Hamming ball of radius at most $\rho n$ has at most $1/\eps$ ... more >>>

TR09-015 | 19th February 2009
Joshua Brody, Amit Chakrabarti

#### A Multi-Round Communication Lower Bound for Gap Hamming and Some Consequences

The Gap-Hamming-Distance problem arose in the context of proving space
lower bounds for a number of key problems in the data stream model. In
this problem, Alice and Bob have to decide whether the Hamming distance
between their $n$-bit input strings is large (i.e., at least $n/2 + \sqrt n$) ... more >>>

TR09-040 | 20th April 2009
Pavel Hrubes, Stasys Jukna, Alexander Kulikov, Pavel Pudlak

#### On convex complexity measures

Khrapchenko's classical lower bound $n^2$ on the formula size of the
parity function~$f$ can be interpreted as designing a suitable
measure of subrectangles of the combinatorial rectangle
$f^{-1}(0)\times f^{-1}(1)$. Trying to generalize this approach we
arrived at the concept of \emph{convex measures}. We prove the
more >>>

TR09-046 | 9th May 2009
Arnab Bhattacharyya, Elena Grigorescu, Kyomin Jung, Sofya Raskhodnikova, David P. Woodruff

#### Transitive-Closure Spanners of the Hypercube and the Hypergrid

Given a directed graph $G = (V,E)$ and an integer $k \geq 1$, a $k$-transitive-closure-spanner ($k$-TC-spanner) of $G$ is a directed graph $H = (V, E_H)$ that has (1) the same transitive-closure as $G$ and (2) diameter at most $k$. Transitive-closure spanners were introduced in \cite{tc-spanners-soda} as a common abstraction ... more >>>

TR09-064 | 3rd August 2009
Harry Buhrman, Lance Fortnow, Rahul Santhanam

#### Unconditional Lower Bounds against Advice

We show several unconditional lower bounds for exponential time classes
against polynomial time classes with advice, including:
\begin{enumerate}
\item For any constant $c$, $\NEXP \not \subseteq \P^{\NP[n^c]}/n^c$
\item For any constant $c$, $\MAEXP \not \subseteq \MA/n^c$
\item $\BPEXP \not \subseteq \BPP/n^{o(1)}$
\end{enumerate}

It was previously unknown even whether $\NEXP \subseteq ... more >>> TR09-073 | 6th September 2009 Vikraman Arvind, Pushkar Joglekar, Srikanth Srinivasan #### On Lower Bounds for Constant Width Arithmetic Circuits The motivation for this paper is to study the complexity of constant-width arithmetic circuits. Our main results are the following. 1. For every k > 1, we provide an explicit polynomial that can be computed by a linear-sized monotone circuit of width 2k but has no subexponential-sized monotone circuit ... more >>> TR09-101 | 20th October 2009 Nitin Saxena #### Progress on Polynomial Identity Testing Polynomial identity testing (PIT) is the problem of checking whether a given arithmetic circuit is the zero circuit. PIT ranks as one of the most important open problems in the intersection of algebra and computational complexity. In the last few years, there has been an impressive progress on this ... more >>> TR09-106 | 28th October 2009 Abhinav Kumar, Satyanarayana V. Lokam, Vijay M. Patankar, Jayalal Sarma #### Using Elimination Theory to construct Rigid Matrices The rigidity of a matrix A for target rank r is the minimum number of entries of A that must be changed to ensure that the rank of the altered matrix is at most r. Since its introduction by Valiant (1977), rigidity and similar rank-robustness functions of matrices have found ... more >>> TR09-126 | 26th November 2009 Eli Ben-Sasson, Venkatesan Guruswami, Tali Kaufman, Madhu Sudan, Michael Viderman #### Locally Testable Codes Require Redundant Testers Revisions: 3 Locally testable codes (LTCs) are error-correcting codes for which membership, in the code, of a given word can be tested by examining it in very few locations. Most known constructions of locally testable codes are linear codes, and give error-correcting codes whose duals have (superlinearly) {\em many} small weight ... more >>> TR10-076 | 18th April 2010 Amit Chakrabarti, Graham Cormode, Ranganath Kondapally, Andrew McGregor #### Information Cost Tradeoffs for Augmented Index and Streaming Language Recognition Revisions: 1 This paper makes three main contributions to the theory of communication complexity and stream computation. First, we present new bounds on the information complexity of AUGMENTED-INDEX. In contrast to analogous results for INDEX by Jain, Radhakrishnan and Sen [J. ACM, 2009], we have to overcome the significant technical challenge that ... more >>> TR10-097 | 16th June 2010 Iddo Tzameret #### Algebraic Proofs over Noncommutative Formulas Revisions: 1 We study possible formulations of algebraic propositional proof systems operating with noncommutative formulas. We observe that a simple formulation gives rise to systems at least as strong as Frege--yielding a semantic way to define a Cook-Reckhow (i.e., polynomially verifiable) algebraic analogue of Frege proofs, different from that given in Buss ... more >>> TR10-191 | 9th December 2010 Andris Ambainis, Loïck Magnin, Martin Roetteler, Jérémie Roland #### Symmetry-assisted adversaries for quantum state generation We introduce a new quantum adversary method to prove lower bounds on the query complexity of the quantum state generation problem. This problem encompasses both, the computation of partial or total functions and the preparation of target quantum states. There has been hope for quite some time that quantum ... more >>> TR10-198 | 13th December 2010 Olaf Beyersdorff, Nicola Galesi, Massimo Lauria, Alexander Razborov #### Parameterized Bounded-Depth Frege is Not Optimal A general framework for parameterized proof complexity was introduced by Dantchev, Martin, and Szeider (FOCS'07). In that framework the parameterized version of any proof system is not fpt-bounded for some technical reasons, but we remark that this question becomes much more interesting if we restrict ourselves to those parameterized contradictions ... more >>> TR11-010 | 1st February 2011 Boris Alexeev, Michael Forbes, Jacob Tsimerman #### Tensor Rank: Some Lower and Upper Bounds The results of Strassen and Raz show that good enough tensor rank lower bounds have implications for algebraic circuit/formula lower bounds. We explore tensor rank lower and upper bounds, focusing on explicit tensors. For odd d, we construct field-independent explicit 0/1 tensors T:[n]^d->F with rank at least 2n^(floor(d/2))+n-Theta(d log n). ... more >>> TR11-026 | 27th February 2011 Evgeny Demenkov, Alexander Kulikov #### An Elementary Proof of$3n-o(n)$Lower Bound on the Circuit Complexity of Affine Dispersers A Boolean function$f \colon \mathbb{F}^n_2 \rightarrow \mathbb{F}_2$is called an affine disperser for sources of dimension$d$, if$f$is not constant on any affine subspace of$\mathbb{F}^n_2$of dimension at least$d$. Recently Ben-Sasson and Kopparty gave an explicit construction of an affine disperser for$d=o(n)$. The main ... more >>> TR11-030 | 9th March 2011 Anna Gal, Andrew Mills #### Three Query Locally Decodable Codes with Higher Correctness Require Exponential Length Locally decodable codes are error correcting codes with the extra property that, in order to retrieve the correct value of just one position of the input with high probability, it is sufficient to read a small number of positions of the corresponding, possibly corrupted ... more >>> TR11-031 | 8th March 2011 Sam Buss, Ryan Williams #### Limits on Alternation-Trading Proofs for Time-Space Lower Bounds This paper characterizes alternation trading based proofs that satisfiability is not in the time and space bounded class$\DTISP(n^c, n^\epsilon)$, for various values$c<2$and$\epsilon<1$. We characterize exactly what can be proved in the$\epsilon=0$case with currently known methods, and prove the conjecture of Williams that$c=2\cos(\pi/7)$is ... more >>> TR11-062 | 18th April 2011 Amit Chakrabarti, Graham Cormode, Andrew McGregor #### Robust Lower Bounds for Communication and Stream Computation We study the communication complexity of evaluating functions when the input data is randomly allocated (according to some known distribution) amongst two or more players, possibly with information overlap. This naturally extends previously studied variable partition models such as the best-case and worst-case partition models. We aim to understand whether ... more >>> TR11-138 | 24th October 2011 Guy Moshkovitz #### Complexity Lower Bounds through Balanced Graph Properties In this paper we present a combinatorial approach for proving complexity lower bounds. We mainly focus on the following instantiation of it. Consider a pair of properties of$m$-edge regular hypergraphs. Suppose they are indistinguishable'' with respect to hypergraphs with$m-t$edges, in the sense that every such hypergraph has ... more >>> TR12-017 | 1st March 2012 Venkatesan Guruswami, Srivatsan Narayanan #### Combinatorial limitations of a strong form of list decoding Revisions: 1 We prove the following results concerning the combinatorics of list decoding, motivated by the exponential gap between the known upper bound (of$O(1/\gamma)$) and lower bound (of$\Omega_p(\log (1/\gamma))$) for the list-size needed to decode up to radius$p$with rate$\gamma$away from capacity, i.e.,$1-h(p)-\gamma$(here$p\in (0,1/2)$... more >>> TR12-042 | 17th April 2012 Chris Beck, Russell Impagliazzo, Shachar Lovett #### Large Deviation Bounds for Decision Trees and Sampling Lower Bounds for AC0-circuits There has been considerable interest lately in the complexity of distributions. Recently, Lovett and Viola (CCC 2011) showed that the statistical distance between a uniform distribution over a good code, and any distribution which can be efficiently sampled by a small bounded-depth AC0 circuit, is inverse-polynomially close to one. That ... more >>> TR12-059 | 14th May 2012 Rahul Santhanam, Ryan Williams #### Uniform Circuits, Lower Bounds, and QBF Algorithms We explore the relationships between circuit complexity, the complexity of generating circuits, and circuit-analysis algorithms. Our results can be roughly divided into three parts: 1. Lower Bounds Against Medium-Uniform Circuits. Informally, a circuit class is medium uniform'' if it can be generated by an algorithmic process that is somewhat complex ... more >>> TR12-062 | 17th May 2012 Ilan Komargodski, Ran Raz #### Average-Case Lower Bounds for Formula Size Revisions: 2 We give an explicit function$h:\{0,1\}^n\to\{0,1\}$such that any deMorgan formula of size$O(n^{2.499})$agrees with$h$on at most$\frac{1}{2} + \epsilon$fraction of the inputs, where$\epsilon$is exponentially small (i.e.$\epsilon = 2^{-n^{\Omega(1)}}$). Previous lower bounds for formula size were obtained for exact computation. The same ... more >>> TR12-093 | 1st July 2012 Charanjit Jutla, Vijay Kumar, Atri Rudra #### On the Circuit Complexity of Composite Galois Field Transformations We study the circuit complexity of linear transformations between Galois fields GF(2^{mn}) and their isomorphic composite fields GF((2^{m})^n). For such a transformation, we show a lower bound of \Omega(mn) on the number of gates required in any circuit consisting of constant-fan-in XOR gates, except for a class of transformations between ... more >>> TR12-132 | 21st October 2012 Yuval Filmus, Massimo Lauria, Jakob Nordström, Noga Ron-Zewi, Neil Thapen #### Space Complexity in Polynomial Calculus During the last decade, an active line of research in proof complexity has been to study space complexity and time-space trade-offs for proofs. Besides being a natural complexity measure of intrinsic interest, space is also an important issue in SAT solving, and so research has mostly focused on weak systems ... more >>> TR12-173 | 8th December 2012 Kfir Barhum, Thomas Holenstein #### A Cookbook for Black-Box Separations and a Recipe for UOWHFs We present a new framework for proving fully black-box separations and lower bounds. We prove a general theorem that facilitates the proofs of fully black-box lower bounds from a one-way function (OWF). Loosely speaking, our theorem says that in order to prove that a fully black-box construction does ... more >>> TR12-178 | 18th December 2012 Paul Beame, Raphael Clifford, Widad Machmouchi #### Sliding Windows With Limited Storage Revisions: 1 We consider time-space tradeoffs for exactly computing frequency moments and order statistics over sliding windows. Given an input of length$2n-1$, the task is to output the function of each window of length$n$, giving$n$outputs in total. Computations over sliding windows are related to direct sum problems except ... more >>> TR12-185 | 29th December 2012 Siu Man Chan, Aaron Potechin #### Tight Bounds for Monotone Switching Networks via Fourier Analysis We prove tight size bounds on monotone switching networks for the NP-complete problem of$k$-clique, and for an explicit monotone problem by analyzing a pyramid structure of height$h$for the P-complete problem of generation. This gives alternative proofs of the separations of m-NC from m-P and of m-NC$^i$from ... more >>> TR13-021 | 5th February 2013 Kristoffer Arnsfelt Hansen, Vladimir Podolskii #### Polynomial threshold functions and Boolean threshold circuits We study the complexity of computing Boolean functions on general Boolean domains by polynomial threshold functions (PTFs). A typical example of a general Boolean domain is$\{1,2\}^n$. We are mainly interested in the length (the number of monomials) of PTFs, with their degree and weight being of secondary interest. We ... more >>> TR13-026 | 11th February 2013 Ankit Gupta, Pritish Kamath, Neeraj Kayal, Ramprasad Saptharishi #### Arithmetic circuits: A chasm at depth three Revisions: 1 We show that, over$\mathbb{C}$, if an$n$-variate polynomial of degree$d = n^{O(1)}$is computable by an arithmetic circuit of size$s$(respectively by an algebraic branching program of size$s$) then it can also be computed by a depth three circuit (i.e. a$\Sigma \Pi \Sigma$-circuit) of size ... more >>> TR13-028 | 14th February 2013 Mrinal Kumar, Gaurav Maheshwari, Jayalal Sarma #### Arithmetic Circuit Lower Bounds via MaxRank We introduce the polynomial coefficient matrix and identify maximum rank of this matrix under variable substitution as a complexity measure for multivariate polynomials. We use our techniques to prove super-polynomial lower bounds against several classes of non-multilinear arithmetic circuits. In particular, we obtain the following results :$\bullet$As ... more >>> TR13-042 | 25th March 2013 Siu Man Chan #### Just a Pebble Game The two-player pebble game of Dymond–Tompa is identified as a barrier for existing techniques to save space or to speed up parallel algorithms for evaluation problems. Many combinatorial lower bounds to study L versus NL and NC versus P under different restricted settings scale in the same way as the ... more >>> TR13-055 | 5th April 2013 David Gamarnik, Madhu Sudan #### Limits of local algorithms over sparse random graphs Local algorithms on graphs are algorithms that run in parallel on the nodes of a graph to compute some global structural feature of the graph. Such algorithms use only local information available at nodes to determine local aspects of the global structure, while also potentially using some randomness. Recent research ... more >>> TR13-058 | 5th April 2013 Ilan Komargodski, Ran Raz, Avishay Tal #### Improved Average-Case Lower Bounds for DeMorgan Formula Size Revisions: 2 We give a function$h:\{0,1\}^n\to\{0,1\}$such that every deMorgan formula of size$n^{3-o(1)}/r^2$agrees with$h$on at most a fraction of$\frac{1}{2}+2^{-\Omega(r)}$of the inputs. This improves the previous average-case lower bound of Komargodski and Raz (STOC, 2013). Our technical contributions include a theorem that shows that the expected ... more >>> TR13-068 | 3rd May 2013 Mrinal Kumar, Shubhangi Saraf #### Lower Bounds for Depth 4 Homogenous Circuits with Bounded Top Fanin We study the class of homogenous$\Sigma\Pi\Sigma\Pi(r)$circuits, which are depth 4 homogenous circuits with top fanin bounded by$r$. We show that any homogenous$\Sigma\Pi\Sigma\Pi(r)$circuit computing the permanent of an$n\times n$matrix must have size at least$\exp\left(n^{\Omega(1/r)}\right)$. In a recent result, Gupta, Kamath, Kayal and ... more >>> TR13-082 | 6th June 2013 Eldar Fischer, Yonatan Goldhirsh, Oded Lachish #### Some properties are not even partially testable For a property$P$and a sub-property$P'$, we say that$P$is$P'$-partially testable with$q$queries if there exists an algorithm that distinguishes, with high probability, inputs in$P'$from inputs$\epsilon$-far from$P$by using$q$queries. There are natural properties that require many queries to test, ... more >>> TR13-091 | 17th June 2013 Neeraj Kayal, Chandan Saha, Ramprasad Saptharishi #### A super-polynomial lower bound for regular arithmetic formulas. We consider arithmetic formulas consisting of alternating layers of addition$(+)$and multiplication$(\times)$gates such that the fanin of all the gates in any fixed layer is the same. Such a formula$\Phi$which additionally has the property that its formal/syntactic degree is at most twice the (total) degree ... more >>> TR13-111 | 17th August 2013 Gregory Valiant, Paul Valiant #### Instance-by-instance optimal identity testing We consider the problem of verifying the identity of a distribution: Given the description of a distribution over a discrete support$p=(p_1,p_2,\ldots,p_n)$, how many samples (independent draws) must one obtain from an unknown distribution,$q$, to distinguish, with high probability, the case that$p=q$from the case that the total ... more >>> TR13-113 | 19th August 2013 Moritz Müller, Stefan Szeider #### Revisiting Space in Proof Complexity: Treewidth and Pathwidth So-called ordered variants of the classical notions of pathwidth and treewidth are introduced and proposed as proof theoretically meaningful complexity measures for the directed acyclic graphs underlying proofs. The ordered pathwidth of a proof is shown to be roughly the same as its formula space. Length-space lower bounds for R(k)-refutations ... more >>> TR13-119 | 2nd September 2013 Emanuele Viola #### Challenges in computational lower bounds We draw two incomplete, biased maps of challenges in computational complexity lower bounds. Our aim is to put these challenges in perspective, and to present some connections which do not seem widely known. more >>> TR13-127 | 15th September 2013 Paul Beame, Raphael Clifford, Widad Machmouchi #### Element Distinctness, Frequency Moments, and Sliding Windows We derive new time-space tradeoff lower bounds and algorithms for exactly computing statistics of input data, including frequency moments, element distinctness, and order statistics, that are simple to calculate for sorted data. In particular, we develop a randomized algorithm for the element distinctness problem whose time$T$and space$S$... more >>> TR13-153 | 8th November 2013 Mrinal Kumar, Shubhangi Saraf #### The Limits of Depth Reduction for Arithmetic Formulas: It's all about the top fan-in In recent years, a very exciting and promising method for proving lower bounds for arithmetic circuits has been proposed. This method combines the method of {\it depth reduction} developed in the works of Agrawal-Vinay [AV08], Koiran [Koi12] and Tavenas [Tav13], and the use of the shifted partial derivative complexity measure ... more >>> TR13-157 | 11th November 2013 Bin Fu #### Derandomizing Polynomial Identity over Finite Fields Implies Super-Polynomial Circuit Lower Bounds for NEXP Revisions: 1 , Comments: 1 We show that derandomizing polynomial identity testing over an arbitrary finite field implies that NEXP does not have polynomial size boolean circuits. In other words, for any finite field F(q) of size q,$PIT_q\in NSUBEXP\Rightarrow NEXP\not\subseteq P/poly$, where$PIT_q$is the polynomial identity testing problem over F(q), and NSUBEXP is ... more >>> TR13-178 | 14th December 2013 Nikolay Vereshchagin #### Randomized communication complexity of appropximating Kolmogorov complexity Revisions: 2 The paper [Harry Buhrman, Michal Koucky, Nikolay Vereshchagin. Randomized Individual Communication Complexity. IEEE Conference on Computational Complexity 2008: 321-331] considered communication complexity of the following problem. Alice has a binary string$x$and Bob a binary string$y$, both of length$n$, and they want to compute or approximate more >>> TR13-181 | 20th December 2013 Mrinal Kumar, Shubhangi Saraf #### Superpolynomial lower bounds for general homogeneous depth 4 arithmetic circuits In this paper, we prove superpolynomial lower bounds for the class of homogeneous depth 4 arithmetic circuits. We give an explicit polynomial in VNP of degree$n$in$n^2$variables such that any homogeneous depth 4 arithmetic circuit computing it must have size$n^{\Omega(\log \log n)}$. Our results extend ... more >>> TR13-185 | 24th December 2013 Fu Li, Iddo Tzameret #### Generating Matrix Identities and Proof Complexity Lower Bounds Revisions: 3 Motivated by the fundamental lower bounds questions in proof complexity, we investigate the complexity of generating identities of matrix rings, and related problems. Specifically, for a field$\mathbb{F}$let$A$be a non-commutative (associative)$\mathbb{F}$-algebra (e.g., the algebra Mat$_d(\mathbb{F})\;$of$d\times d$matrices over$\mathbb{F}$). We say that a non-commutative ... more >>> TR14-014 | 28th January 2014 Olaf Beyersdorff, Leroy Chew #### The Complexity of Theorem Proving in Circumscription and Minimal Entailment Circumscription is one of the main formalisms for non-monotonic reasoning. It uses reasoning with minimal models, the key idea being that minimal models have as few exceptions as possible. In this contribution we provide the first comprehensive proof-complexity analysis of different proof systems for propositional circumscription. In particular, we investigate ... more >>> TR14-045 | 7th April 2014 Mrinal Kumar, Shubhangi Saraf #### On the power of homogeneous depth 4 arithmetic circuits Revisions: 2 We prove exponential lower bounds on the size of homogeneous depth 4 arithmetic circuits computing an explicit polynomial in$VP$. Our results hold for the {\it Iterated Matrix Multiplication} polynomial - in particular we show that any homogeneous depth 4 circuit computing the$(1,1)$entry in the product of$n$... more >>> TR14-052 | 14th April 2014 Joshua Grochow, Toniann Pitassi #### Circuit complexity, proof complexity, and polynomial identity testing We introduce a new and very natural algebraic proof system, which has tight connections to (algebraic) circuit complexity. In particular, we show that any super-polynomial lower bound on any Boolean tautology in our proof system implies that the permanent does not have polynomial-size algebraic circuits ($VNP \neq VP$). As a ... more >>> TR14-058 | 20th April 2014 Ilya Volkovich #### On Learning, Lower Bounds and (un)Keeping Promises We extend the line of research initiated by Fortnow and Klivans \cite{FortnowKlivans09} that studies the relationship between efficient learning algorithms and circuit lower bounds. In \cite{FortnowKlivans09}, it was shown that if a Boolean circuit class$\mathcal{C}$has an efficient \emph{deterministic} exact learning algorithm, (i.e. an algorithm that uses membership and ... more >>> TR14-067 | 4th May 2014 Venkatesan Guruswami, Madhu Sudan, Ameya Velingker, Carol Wang #### Limitations on Testable Affine-Invariant Codes in the High-Rate Regime Locally testable codes (LTCs) of constant distance that allow the tester to make a linear number of queries have become the focus of attention recently, due to their elegant connections to hardness of approximation. In particular, the binary Reed-Muller code of block length$N$and distance$d$is known to ... more >>> TR14-080 | 11th June 2014 Stasys Jukna #### Lower Bounds for Tropical Circuits and Dynamic Programs Revisions: 1 Tropical circuits are circuits with Min and Plus, or Max and Plus operations as gates. Their importance stems from their intimate relation to dynamic programming algorithms. The power of tropical circuits lies somewhere between that of monotone boolean circuits and monotone arithmetic circuits. In this paper we present some lower ... more >>> TR14-141 | 24th October 2014 Shachar Lovett #### Linear codes cannot approximate the network capacity within any constant factor Network coding studies the capacity of networks to carry information, when internal nodes are allowed to actively encode information. It is known that for multi-cast networks, the network coding capacity can be achieved by linear codes. It is also known not to be true for general networks. The best separation ... more >>> TR14-153 | 14th November 2014 Clement Canonne, Venkatesan Guruswami, Raghu Meka, Madhu Sudan #### Communication with Imperfectly Shared Randomness Revisions: 2 The communication complexity of many fundamental problems reduces greatly when the communicating parties share randomness that is independent of the inputs to the communication task. Natural communication processes (say between humans) however often involve large amounts of shared correlations among the communicating players, but rarely allow for perfect sharing of ... more >>> TR14-154 | 20th November 2014 Andris Ambainis, Yuval Filmus, Francois Le Gall #### Fast Matrix Multiplication: Limitations of the Laser Method Until a few years ago, the fastest known matrix multiplication algorithm, due to Coppersmith and Winograd (1990), ran in time$O(n^{2.3755})$. Recently, a surge of activity by Stothers, Vassilevska-Williams, and Le Gall has led to an improved algorithm running in time$O(n^{2.3729})$. These algorithms are obtained by analyzing higher ... more >>> TR14-156 | 26th November 2014 Jayadev Acharya, Clement Canonne, Gautam Kamath #### A Chasm Between Identity and Equivalence Testing with Conditional Queries Revisions: 2 A recent model for property testing of probability distributions enables tremendous savings in the sample complexity of testing algorithms, by allowing them to condition the sampling on subsets of the domain. In particular, Canonne et al. showed that, in this setting, testing identity of an unknown distribution$D$(i.e., ... more >>> TR15-028 | 27th February 2015 Lila Fontes, Rahul Jain, Iordanis Kerenidis, Sophie Laplante, Mathieu Laurière, Jérémie Roland #### Relative Discrepancy does not separate Information and Communication Complexity Does the information complexity of a function equal its communication complexity? We examine whether any currently known techniques might be used to show a separation between the two notions. Recently, Ganor et al. provided such a separation in the distributional setting for a specific input distribution ?. We show that ... more >>> TR15-030 | 6th March 2015 Mahdi Cheraghchi, Elena Grigorescu, Brendan Juba, Karl Wimmer, Ning Xie ####${\mathrm{AC}^{0} \circ \mathrm{MOD}_2}$lower bounds for the Boolean Inner Product Revisions: 1$\mathrm{AC}^{0} \circ \mathrm{MOD}_2$circuits are$\mathrm{AC}^{0}$circuits augmented with a layer of parity gates just above the input layer. We study the$\mathrm{AC}^{0} \circ \mathrm{MOD}_2$circuit lower bound for computing the Boolean Inner Product functions. Recent works by Servedio and Viola (ECCC TR12-144) and Akavia et al. (ITCS 2014) have ... more >>> TR15-070 | 22nd April 2015 Himanshu Tyagi, Shaileshh Venkatakrishnan , Pramod Viswanath, Shun Watanabe #### Information Complexity Density and Simulation of Protocols Revisions: 1 A simulation of an interactive protocol entails the use of an interactive communication to produce the output of the protocol to within a fixed statistical distance$\epsilon$. Recent works in the TCS community have propagated that the information complexity of the protocol plays a central role in characterizing the minimum ... more >>> TR15-109 | 1st July 2015 Mrinal Kumar, Ramprasad Saptharishi #### An exponential lower bound for homogeneous depth-5 circuits over finite fields In this paper, we show exponential lower bounds for the class of homogeneous depth-$5$circuits over all small finite fields. More formally, we show that there is an explicit family$\{P_d : d \in N\}$of polynomials in$VNP$, where$P_d$is of degree$d$in$n = d^{O(1)}$variables, ... more >>> TR15-113 | 9th July 2015 Amit Chakrabarti, Tony Wirth #### Incidence Geometries and the Pass Complexity of Semi-Streaming Set Cover Set cover, over a universe of size$n$, may be modelled as a data-streaming problem, where the$m$sets that comprise the instance are to be read one by one. A semi-streaming algorithm is allowed only$O(n \text{ poly}\{\log n, \log m\})$space to process this ... more >>> TR15-115 | 20th July 2015 Ilya Volkovich #### A Guide to Learning Arithmetic Circuits An \emph{arithmetic circuit} is a directed acyclic graph in which the operations are$\{+,\times\}$. In this paper, we exhibit several connections between learning algorithms for arithmetic circuits and other problems. In particular, we show that: \begin{enumerate} \item Efficient learning algorithms for arithmetic circuit classes imply explicit exponential lower bounds. ... more >>> TR15-123 | 31st July 2015 Xi Chen, Igor Carboni Oliveira, Rocco Servedio #### Addition is exponentially harder than counting for shallow monotone circuits Let$U_{k,N}$denote the Boolean function which takes as input$k$strings of$N$bits each, representing$k$numbers$a^{(1)},\dots,a^{(k)}$in$\{0,1,\dots,2^{N}-1\}$, and outputs 1 if and only if$a^{(1)} + \cdots + a^{(k)} \geq 2^N.$Let THR$_{t,n}$denote a monotone unweighted threshold gate, i.e., the Boolean function which takes ... more >>> TR15-127 | 7th August 2015 Stasys Jukna, Georg Schnitger #### On the Optimality of Bellman--Ford--Moore Shortest Path Algorithm Revisions: 1 We prove a general lower bound on the size of branching programs over any semiring of zero characteristic, including the (min,+) semiring. Using it, we show that the classical dynamic programming algorithm of Bellman, Ford and Moore for the shortest s-t path problem is optimal, if only Min and Sum ... more >>> TR15-133 | 12th August 2015 Olaf Beyersdorff, Ilario Bonacina, Leroy Chew #### Lower bounds: from circuits to QBF proof systems A general and long-standing belief in the proof complexity community asserts that there is a close connection between progress in lower bounds for Boolean circuits and progress in proof size lower bounds for strong propositional proof systems. Although there are famous examples where a transfer from ideas and techniques from ... more >>> TR15-134 | 19th August 2015 Fu Li, Iddo Tzameret, Zhengyu Wang #### Characterizing Propositional Proofs as Non-Commutative Formulas Does every Boolean tautology have a short propositional-calculus proof? Here, a propositional-calculus (i.e., Frege) proof is any proof starting from a set of axioms and deriving new Boolean formulas using a fixed set of sound derivation rules. Establishing any super-polynomial size lower bound on Frege proofs (in terms of the ... more >>> TR15-152 | 16th September 2015 Olaf Beyersdorff, Leroy Chew, Meena Mahajan, Anil Shukla #### Are Short Proofs Narrow? QBF Resolution is not Simple. The groundbreaking paper Short proofs are narrow - resolution made simple' by Ben-Sasson and Wigderson (J. ACM 2001) introduces what is today arguably the main technique to obtain resolution lower bounds: to show a lower bound for the width of proofs. Another important measure for resolution is space, and in ... more >>> TR15-154 | 22nd September 2015 Neeraj Kayal, Vineet Nair, Chandan Saha #### Separation between Read-once Oblivious Algebraic Branching Programs (ROABPs) and Multilinear Depth Three Circuits We show an exponential separation between two well-studied models of algebraic computation, namely read-once oblivious algebraic branching programs (ROABPs) and multilinear depth three circuits. In particular we show the following: 1. There exists an explicit$n$-variate polynomial computable by linear sized multilinear depth three circuits (with only two product gates) ... more >>> TR15-166 | 17th October 2015 Magnus Gausdal Find, Alexander Golovnev, Edward Hirsch, Alexander Kulikov #### A better-than-$3n$lower bound for the circuit complexity of an explicit function Revisions: 1 We consider Boolean circuits over the full binary basis. We prove a$(3+\frac{1}{86})n-o(n)$lower bound on the size of such a circuit for an explicitly defined predicate, namely an affine disperser for sublinear dimension. This improves the$3n-o(n)$bound of Norbert Blum (1984). The proof is based on the gate ... more >>> TR15-170 | 26th October 2015 Alexander Golovnev, Alexander Kulikov #### Weighted gate elimination: Boolean dispersers for quadratic varieties imply improved circuit lower bounds In this paper we motivate the study of Boolean dispersers for quadratic varieties by showing that an explicit construction of such objects gives improved circuit lower bounds. An$(n,k,s)$-quadratic disperser is a function on$n$variables that is not constant on any subset of$\mathbb{F}_2^n$of size at least$s$... more >>> TR15-171 | 28th October 2015 Joshua Grochow #### Monotone projection lower bounds from extended formulation lower bounds Revisions: 2 , Comments: 1 In this short note, we show that the permanent is not complete for non-negative polynomials in$VNP_{\mathbb{R}}$under monotone p-projections. In particular, we show that Hamilton Cycle polynomial and the cut polynomials are not monotone p-projections of the permanent. To prove this we introduce a new connection between monotone projections ... more >>> TR15-181 | 13th November 2015 Neeraj Kayal, Chandan Saha, Sébastien Tavenas #### On the size of homogeneous and of depth four formulas with low individual degree Let$r \geq 1$be an integer. Let us call a polynomial$f(x_1, x_2,\ldots, x_N) \in \mathbb{F}[\mathbf{x}]$as a multi-$r$-ic polynomial if the degree of$f$with respect to any variable is at most$r$(this generalizes the notion of multilinear polynomials). We investigate arithmetic circuits in which the output ... more >>> TR15-194 | 30th November 2015 Mrinal Kumar, Shubhangi Saraf #### Arithmetic circuits with locally low algebraic rank Revisions: 1 In recent years there has been a flurry of activity proving lower bounds for homogeneous depth-4 arithmetic circuits [GKKS13, FLMS14, KLSS14, KS14c], which has brought us very close to statements that are known to imply VP$\neq$VNP. It is a big question to go beyond homogeneity, and in ... more >>> TR16-005 | 22nd January 2016 Olaf Beyersdorff, Leroy Chew, Mikolas Janota #### Extension Variables in QBF Resolution We investigate two QBF resolution systems that use extension variables: weak extended Q-resolution, where the extension variables are quantified at the innermost level, and extended Q-resolution, where the extension variables can be placed inside the quantifier prefix. These systems have been considered previously by Jussila et al. '07 who ... more >>> TR16-011 | 27th January 2016 Olaf Beyersdorff, Ján Pich #### Understanding Gentzen and Frege systems for QBF Recently Beyersdorff, Bonacina, and Chew (ITCS'16) introduced a natural class of Frege systems for quantified Boolean formulas (QBF) and showed strong lower bounds for restricted versions of these systems. Here we provide a comprehensive analysis of the new extended Frege system from Beyersdorff et al., denoted EF+$\forall$red, which is a ... more >>> TR16-019 | 5th February 2016 Ran Raz #### Fast Learning Requires Good Memory: A Time-Space Lower Bound for Parity Learning We prove that any algorithm for learning parities requires either a memory of quadratic size or an exponential number of samples. This proves a recent conjecture of Steinhardt, Valiant and Wager and shows that for some learning problems a large storage space is crucial. More formally, in the problem of ... more >>> TR16-022 | 22nd February 2016 Alexander Golovnev, Alexander Kulikov, Alexander Smal, Suguru Tamaki #### Circuit size lower bounds and #SAT upper bounds through a general framework Revisions: 2 Most of the known lower bounds for binary Boolean circuits with unrestricted depth are proved by the gate elimination method. The most efficient known algorithms for the #SAT problem on binary Boolean circuits use similar case analyses to the ones in gate elimination. Chen and Kabanets recently showed that the ... more >>> TR16-033 | 10th March 2016 Venkatesan Guruswami, Jaikumar Radhakrishnan #### Tight bounds for communication assisted agreement distillation Suppose Alice holds a uniformly random string$X \in \{0,1\}^N$and Bob holds a noisy version$Y$of$X$where each bit of$X$is flipped independently with probability$\epsilon \in [0,1/2]$. Alice and Bob would like to extract a common random string of min-entropy at least$k$. In this ... more >>> TR16-041 | 17th March 2016 Johan Hastad #### An average-case depth hierarchy theorem for higher depth We extend the recent hierarchy results of Rossman, Servedio and Tan \cite{rst15} to any$d \leq \frac {c \log n}{\log {\log n}}$for an explicit constant$c$. To be more precise, we prove that for any such$d$there is a function$F_d$that is computable by a read-once formula ... more >>> TR16-045 | 22nd March 2016 Michael Forbes, Mrinal Kumar, Ramprasad Saptharishi #### Functional lower bounds for arithmetic circuits and connections to boolean circuit complexity We say that a circuit$C$over a field$F$functionally computes an$n$-variate polynomial$P \in F[x_1, x_2, \ldots, x_n]$if for every$x \in \{0,1\}^n$we have that$C(x) = P(x)$. This is in contrast to {syntactically} computing$P$, when$C \equiv P$as formal polynomials. In this ... more >>> TR16-058 | 12th April 2016 Boaz Barak, Samuel Hopkins, Jonathan Kelner, Pravesh Kothari, Ankur Moitra, Aaron Potechin #### A Nearly Tight Sum-of-Squares Lower Bound for the Planted Clique Problem We prove that with high probability over the choice of a random graph$G$from the Erd\H{o}s-R\'enyi distribution$G(n,1/2)$, the$n^{O(d)}$-time degree$d$Sum-of-Squares semidefinite programming relaxation for the clique problem will give a value of at least$n^{1/2-c(d/\log n)^{1/2}}$for some constant$c>0$. This yields a nearly tight ... more >>> TR16-064 | 19th April 2016 Stephen A. Cook, Toniann Pitassi, Robert Robere, Benjamin Rossman #### Exponential Lower Bounds for Monotone Span Programs Monotone span programs are a linear-algebraic model of computation which were introduced by Karchmer and Wigderson in 1993. They are known to be equivalent to linear secret sharing schemes, and have various applications in complexity theory and cryptography. Lower bounds for monotone span programs have been difficult to obtain because ... more >>> TR16-070 | 24th April 2016 Mika Göös, Rahul Jain, Thomas Watson #### Extension Complexity of Independent Set Polytopes Revisions: 1 We exhibit an$n$-node graph whose independent set polytope requires extended formulations of size exponential in$\Omega(n/\log n)$. Previously, no explicit examples of$n$-dimensional$0/1$-polytopes were known with extension complexity larger than exponential in$\Theta(\sqrt{n})$. Our construction is inspired by a relatively little-known connection between extended formulations and (monotone) circuit ... more >>> TR16-076 | 27th April 2016 Krishnamoorthy Dinesh, Sajin Koroth, Jayalal Sarma #### Characterization and Lower Bounds for Branching Program Size using Projective Dimension Revisions: 2 We study projective dimension, a graph parameter (denoted by$pd(G)$for a graph$G$), introduced by (Pudlak, Rodl 1992), who showed that proving lower bounds for$pd(G_f)$for bipartite graphs$G_f$associated with a Boolean function$f$imply size lower bounds for branching programs computing$f$. Despite several attempts (Pudlak, ... more >>> TR16-094 | 6th June 2016 Guillaume Lagarde, Guillaume Malod #### Non-commutative computations: lower bounds and polynomial identity testing Comments: 1 In the setting of non-commutative arithmetic computations, we define a class of circuits that gener- alize algebraic branching programs (ABP). This model is called unambiguous because it captures the polynomials in which all monomials are computed in a similar way (that is, all the parse trees are iso- morphic). We ... more >>> TR16-098 | 16th June 2016 Michael Forbes, Amir Shpilka, Iddo Tzameret, Avi Wigderson #### Proof Complexity Lower Bounds from Algebraic Circuit Complexity We give upper and lower bounds on the power of subsystems of the Ideal Proof System (IPS), the algebraic proof system recently proposed by Grochow and Pitassi, where the circuits comprising the proof come from various restricted algebraic circuit classes. This mimics an established research direction in the ... more >>> TR16-107 | 17th July 2016 Nathanael Fijalkow #### Lower Bounds for Alternating Online Space Complexity Revisions: 1 The notion of online space complexity, introduced by Karp in 1967, quantifies the amount of states required to solve a given problem using an online algorithm, represented by a machine which scans the input exactly once from left to right. In this paper, we study alternating machines as introduced by ... more >>> TR16-131 | 21st August 2016 Andrej Bogdanov, Siyao Guo, Ilan Komargodski #### Threshold Secret Sharing Requires a Linear Size Alphabet We prove that for every$n$and$1 < t < n$any$t$-out-of-$n$threshold secret sharing scheme for one-bit secrets requires share size$\log(t + 1)$. Our bound is tight when$t = n - 1$and$n$is a prime power. In 1990 Kilian and Nisan proved ... more >>> TR16-137 | 3rd September 2016 Mrinal Kumar, Ramprasad Saptharishi #### Finer separations between shallow arithmetic circuits In this paper, we show that there is a family of polynomials$\{P_n\}$, where$P_n$is a polynomial in$n$variables of degree at most$d = O(\log^2 n)$, such that 1.$P_n$can be computed by linear sized homogeneous depth-$5$circuits. 2.$P_n$can be computed by ... more >>> TR16-151 | 26th September 2016 Amir Yehudayoff #### Pointer chasing via triangular discrimination We prove an essentially sharp$\tilde\Omega(n/k)$lower bound on the$k$-round distributional complexity of the$k$-step pointer chasing problem under the uniform distribution, when Bob speaks first. This is an improvement over Nisan and Wigderson's$\tilde \Omega(n/k^2)$lower bound. A key part of the proof is using triangular discrimination instead ... more >>> TR16-175 | 8th November 2016 Pavel Pudlak, Neil Thapen #### Random resolution refutations Revisions: 2 We study the \emph{random resolution} refutation system defined in~[Buss et al. 2014]. This attempts to capture the notion of a resolution refutation that may make mistakes but is correct most of the time. By proving the equivalence of several different definitions, we show that this concept is robust. On the ... more >>> TR17-009 | 19th January 2017 Joshua Grochow, Mrinal Kumar, Michael Saks, Shubhangi Saraf #### Towards an algebraic natural proofs barrier via polynomial identity testing We observe that a certain kind of algebraic proof - which covers essentially all known algebraic circuit lower bounds to date - cannot be used to prove lower bounds against VP if and only if what we call succinct hitting sets exist for VP. This is analogous to the Razborov-Rudich ... more >>> TR17-081 | 2nd May 2017 Badih Ghazi, Madhu Sudan #### The Power of Shared Randomness in Uncertain Communication In a recent work (Ghazi et al., SODA 2016), the authors with Komargodski and Kothari initiated the study of communication with contextual uncertainty, a setup aiming to understand how efficient communication is possible when the communicating parties imperfectly share a huge context. In this setting, Alice is given a function ... more >>> TR17-117 | 20th July 2017 Dmitry Itsykson, Alexander Knop #### Hard satisfiable formulas for splittings by linear combinations Itsykson and Sokolov in 2014 introduced the class of DPLL($\oplus$) algorithms that solve Boolean satisfiability problem using the splitting by linear combinations of variables modulo 2. This class extends the class of DPLL algorithms that split by variables. DPLL($\oplus$) algorithms solve in polynomial time systems of linear equations modulo two ... more >>> TR17-120 | 31st July 2017 Paul Beame, Shayan Oveis Gharan, Xin Yang #### Time-Space Tradeoffs for Learning from Small Test Spaces: Learning Low Degree Polynomial Functions Revisions: 1 We develop an extension of recently developed methods for obtaining time-space tradeoff lower bounds for problems of learning from random test samples to handle the situation where the space of tests is signficantly smaller than the space of inputs, a class of learning problems that is not handled by prior ... more >>> TR17-136 | 10th September 2017 Salman Beigi, Andrej Bogdanov, Omid Etesami, Siyao Guo #### Complete Classi fication of Generalized Santha-Vazirani Sources Let$\mathcal{F}$be a finite alphabet and$\mathcal{D}$be a finite set of distributions over$\mathcal{F}$. A Generalized Santha-Vazirani (GSV) source of type$(\mathcal{F}, \mathcal{D})$, introduced by Beigi, Etesami and Gohari (ICALP 2015, SICOMP 2017), is a random sequence$(F_1, \dots, F_n)$in$\mathcal{F}^n$, where$F_i$is a sample from ... more >>> TR17-156 | 15th October 2017 Suryajith Chillara, Nutan Limaye, Srikanth Srinivasan #### Small-depth Multilinear Formula Lower Bounds for Iterated Matrix Multiplication, with Applications The complexity of Iterated Matrix Multiplication is a central theme in Computational Complexity theory, as the problem is closely related to the problem of separating various complexity classes within$\mathrm{P}$. In this paper, we study the algebraic formula complexity of multiplying$d$many$2\times 2$matrices, denoted$\mathrm{IMM}_{d}$, and show ... more >>> TR17-183 | 28th November 2017 Sivakanth Gopi, Venkatesan Guruswami, Sergey Yekhanin #### On Maximally Recoverable Local Reconstruction Codes In recent years the explosion in the volumes of data being stored online has resulted in distributed storage systems transitioning to erasure coding based schemes. Local Reconstruction Codes (LRCs) have emerged as the codes of choice for these applications. An$(n,r,h,a,q)$-LRC is a$q$-ary code, where encoding is as a ... more >>> TR17-188 | 22nd December 2017 Cody Murray, Ryan Williams #### Circuit Lower Bounds for Nondeterministic Quasi-Polytime: An Easy Witness Lemma for NP and NQP We prove that if every problem in$NP$has$n^k$-size circuits for a fixed constant$k$, then for every$NP$-verifier and every yes-instance$x$of length$n$for that verifier, the verifier's search space has an$n^{O(k^3)}$-size witness circuit: a witness for$x$that can be encoded with a circuit ... more >>> TR18-049 | 14th March 2018 Stasys Jukna, Hannes Seiwert #### Greedy can also beat pure dynamic programming Revisions: 1 Many dynamic programming algorithms are pure'' in that they only use min or max and addition operations in their recursion equations. The well known greedy algorithm of Kruskal solves the minimum weight spanning tree problem on$n$-vertex graphs using only$O(n^2\log n)$operations. We prove that any pure DP algorithm ... more >>> TR18-062 | 7th April 2018 Suryajith Chillara, Christian Engels, Nutan Limaye, Srikanth Srinivasan #### A Near-Optimal Depth-Hierarchy Theorem for Small-Depth Multilinear Circuits We study the size blow-up that is necessary to convert an algebraic circuit of product-depth$\Delta+1$to one of product-depth$\Delta$in the multilinear setting. We show that for every positive$\Delta = \Delta(n) = o(\log n/\log \log n),$there is an explicit multilinear polynomial$P^{(\Delta)}$on$n$variables that ... more >>> TR18-094 | 2nd May 2018 Amit Levi, Erik Waingarten #### Lower Bounds for Tolerant Junta and Unateness Testing via Rejection Sampling of Graphs We introduce a new model for testing graph properties which we call the \emph{rejection sampling model}. We show that testing bipartiteness of$n$-nodes graphs using rejection sampling queries requires complexity$\widetilde{\Omega}(n^2)$. Via reductions from the rejection sampling model, we give three new lower bounds for tolerant testing of Boolean functions ... more >>> TR18-102 | 15th May 2018 Olaf Beyersdorff, Leroy Chew, Judith Clymo, Meena Mahajan #### Short Proofs in QBF Expansion For quantified Boolean formulas (QBF) there are two main different approaches to solving: QCDCL and expansion solving. In this paper we compare the underlying proof systems and show that expansion systems admit strictly shorter proofs than CDCL systems for formulas of bounded quantifier complexity, thus pointing towards potential advantages of ... more >>> TR18-127 | 9th July 2018 Stasys Jukna, Hannes Seiwert #### Approximation Limitations of Tropical Circuits We develop general lower bound arguments for approximating tropical (min,+) and (max,+) circuits, and use them to prove the first non-trivial, even super-polynomial, lower bounds on the size of such circuits approximating some explicit optimization problems. In particular, these bounds show that the approximation powers of pure dynamic programming algorithms ... more >>> TR18-139 | 10th August 2018 Igor Carboni Oliveira, Rahul Santhanam #### Hardness Magnification for Natural Problems We show that for several natural problems of interest, complexity lower bounds that are barely non-trivial imply super-polynomial or even exponential lower bounds in strong computational models. We term this phenomenon "hardness magnification". Our examples of hardness magnification include: 1. Let MCSP$[s]$be the decision problem whose YES instances are ... more >>> TR18-154 | 7th September 2018 Stasys Jukna, Andrzej Lingas #### Lower Bounds for Circuits of Bounded Negation Width We consider Boolean circuits over$\{\lor,\land,\neg\}$with negations applied only to input variables. To measure the amount of negation'' in such circuits, we introduce the concept of their `negation width.'' In particular, a circuit computing a monotone Boolean function$f(x_1,\ldots,x_n)$has negation width$w$if no nonzero term produced (purely ... more >>> TR18-180 | 3rd November 2018 Nathanael Fijalkow, Guillaume Lagarde, Pierre Ohlmann, Olivier Serre #### Lower bounds for arithmetic circuits via the Hankel matrix We study the complexity of representing polynomials by arithmetic circuits in both the commutative and the non-commutative settings. Our approach goes through a precise understanding of the more restricted setting where multiplication is not associative, meaning that we distinguish$(xy)z$from$x(yz)\$.

Our first and main conceptual result is a ... more >>>

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