Electronic Colloquium on Computational Complexity
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REPORTS > 2010:
All reports in year 2010:
TR10-001 | 30th December 2009
Iftach Haitner, Mohammad Mahmoody, David Xiao

A New Sampling Protocol and Applications to Basing Cryptographic Primitives on the Hardness of $NP$

We investigate the question of what languages can be decided efficiently with the help of a recursive collision-finding oracle. Such an oracle can be used to break collision-resistant hash functions or, more generally, statistically hiding commitments. The oracle we consider, $Sam_d$ where $d$ is the recursion depth, is based on ... more >>>

TR10-002 | 4th January 2010
Ran Raz

Tensor-Rank and Lower Bounds for Arithmetic Formulas

We show that any explicit example for a tensor $A:[n]^r \rightarrow \mathbb{F}$ with tensor-rank
$\geq n^{r \cdot (1- o(1))}$,
(where $r = r(n) \leq \log n / \log \log n$), implies an explicit super-polynomial lower bound for the size of general arithmetic formulas over $\mathbb{F}$. This shows that strong enough ... more >>>

TR10-003 | 6th January 2010
Venkatesan Guruswami, Johan Hastad, Swastik Kopparty

On the List-Decodability of Random Linear Codes

For every fixed finite field $\F_q$, $p \in (0,1-1/q)$ and $\varepsilon >
0$, we prove that with high probability a random subspace $C$ of
$\F_q^n$ of dimension $(1-H_q(p)-\varepsilon)n$ has the
property that every Hamming ball of radius $pn$ has at most
$O(1/\varepsilon)$ codewords.

This ... more >>>

TR10-004 | 6th January 2010
Eli Ben-Sasson, Michael Viderman

Low Rate Is Insufficient for Local Testability

Revisions: 3

Locally testable codes (LTCs) are error-correcting codes for which membership of a given word in the code can be tested probabilistically by examining it in very few locations.
Kaufman and Sudan \cite{KS07} proved that sparse, low-bias linear codes are locally testable (in particular sparse random codes are locally testable).
Kopparty ... more >>>

TR10-005 | 3rd January 2010
Haitao Jiang, Binhai Zhu

Weak Kernels

Revisions: 7

In this paper, we formalize a folklore concept and formally define
{\em weak kernels} for fixed-parameter computation. We show that a
problem has a (traditional) kernel then it also has a weak kernel.
It is unknown yet whether the converse is always true. On the other hand,
for a problem ... more >>>

TR10-006 | 11th January 2010
YI WU, Ryan O'Donnell, David Zuckerman, Parikshit Gopalan

Fooling functions of halfspaces under product distributions

Revisions: 2

We construct pseudorandom generators that fool functions of halfspaces (threshold functions) under a very broad class of product distributions. This class includes not only familiar cases such as the uniform distribution on the discrete cube, the uniform distribution on the solid cube, and the multivariate Gaussian distribution, but also includes ... more >>>

TR10-007 | 12th January 2010
Atri Rudra, steve uurtamo

Two Theorems in List Decoding

We prove the following results concerning the list decoding of error-correcting codes:

We show that for any code with a relative distance of $\delta$
(over a large enough alphabet), the
following result holds for random errors: With high probability,
for a $\rho\le \delta -\eps$ fraction of random errors (for any ... more >>>

TR10-008 | 13th January 2010
Yijia Chen, Joerg Flum

On optimal proof systems and logics for PTIME

Revisions: 1

We prove that TAUT has a $p$-optimal proof system if and only if $L_\le$, a logic introduced in [Gurevich, 88], is a P-bounded logic for P. Furthermore, using the method developed in [Chen and Flum, 10], we show that TAUT has no \emph{effective} $p$-optimal proof system under some reasonable complexity-theoretic ... more >>>

TR10-009 | 13th January 2010
A. Pavan, Raghunath Tewari, Vinodchandran Variyam

On the Power of Unambiguity in Logspace

We report progress on the \NL\ vs \UL\ problem.
\item[-] We show unconditionally that the complexity class $\ReachFewL\subseteq\UL$. This improves on the earlier known upper bound $\ReachFewL \subseteq \FewL$.
\item[-] We investigate the complexity of min-uniqueness - a central
notion in studying the \NL\ vs \UL\ problem.
more >>>

TR10-010 | 16th January 2010
Shachar Lovett

Equivalence of polynomial conjectures in additive combinatorics

We study two conjectures in additive combinatorics. The first is the polynomial Freiman-Ruzsa conjecture, which relates to the structure of sets with small doubling. The second is the inverse Gowers conjecture for $U^ $, which relates to functions which locally look like quadratics. In both cases a weak form, with ... more >>>

TR10-011 | 22nd January 2010
Amir Shpilka, Ilya Volkovich

Read-Once Polynomial Identity Testing

An \emph{arithmetic read-once formula} (ROF for short) is a
formula (a circuit whose underlying graph is a tree) in which the
operations are $\{+,\times\}$ and such that every input variable
labels at most one leaf. A \emph{preprocessed ROF} (PROF for
short) is a ROF in which we are allowed to ... more >>>

TR10-012 | 27th January 2010
Zeev Dvir, Parikshit Gopalan, Sergey Yekhanin

Matching Vector Codes

Revisions: 1

An $(r,\delta,\epsilon)$-locally decodable code encodes a $k$-bit message $x$ to an $N$-bit codeword $C(x),$ such that for every $i\in [k],$ the $i$-th message bit can be recovered with probability $1-\epsilon,$ by a randomized decoding procedure that reads only $r$ bits, even if the codeword $C(x)$ is corrupted in up to ... more >>>

TR10-013 | 31st January 2010
Nitin Saxena, C. Seshadhri

From Sylvester-Gallai Configurations to Rank Bounds: Improved Black-box Identity Test for Depth-3 Circuits

Revisions: 1

We study the problem of identity testing for depth-3 circuits, over the
field of reals, of top fanin k and degree d (called sps(k,d)
identities). We give a new structure theorem for such identities and improve
the known deterministic d^{k^k}-time black-box identity test (Kayal &
Saraf, FOCS 2009) to one ... more >>>

TR10-014 | 2nd February 2010
Daniele Micciancio, Panagiotis Voulgaris

A Deterministic Single Exponential Time Algorithm for Most Lattice Problems based on Voronoi Cell Computations

Revisions: 1

We give deterministic $2^{O(n)}$-time algorithms to solve all the most important computational problems on point lattices in NP, including the Shortest Vector Problem (SVP), Closest Vector Problem (CVP), and Shortest Independent Vectors Problem (SIVP).
This improves the $n^{O(n)}$ running time of the best previously known algorithms for CVP (Kannan, ... more >>>

TR10-015 | 8th February 2010
Maurice Jansen, Youming Qiao, Jayalal Sarma

Deterministic Black-Box Identity Testing $\pi$-Ordered Algebraic Branching Programs

In this paper we study algebraic branching programs (ABPs) with restrictions on the order and the number of reads of variables in the program. Given a permutation $\pi$ of $n$ variables, for a $\pi$-ordered ABP ($\pi$-OABP), for any directed path $p$ from source to sink, a variable can appear at ... more >>>

TR10-016 | 22nd December 2009
Alexander Fanghänel, Sascha Geulen, Martin Hoefer, Berthold Vöcking

Online Capacity Maximization in Wireless Networks

In this paper we study a dynamic version of capacity maximization in the physical model of wireless communication. In our model, requests for connections between pairs of points in Euclidean space of constant dimension $d$ arrive iteratively over time. When a new request arrives, an online algorithm needs to decide ... more >>>

TR10-017 | 10th February 2010
Jonathan Ullman, Salil Vadhan

PCPs and the Hardness of Generating Synthetic Data

Revisions: 4

Assuming the existence of one-way functions, we show that there is no
polynomial-time, differentially private algorithm $A$ that takes a database
$D\in (\{0,1\}^d)^n$ and outputs a ``synthetic database'' $\hat{D}$ all of whose two-way
marginals are approximately equal to those of $D$. (A two-way marginal is the fraction
of database rows ... more >>>

TR10-018 | 15th February 2010
Vitaly Feldman

A Complete Characterization of Statistical Query Learning with Applications to Evolvability

Revisions: 1

Statistical query (SQ) learning model of Kearns (1993) is a natural restriction of the PAC learning model in which a learning algorithm is allowed to obtain estimates of statistical properties of the examples but cannot see the examples themselves. We describe a new and simple characterization of the query complexity ... more >>>

TR10-019 | 19th February 2010
Andrew Drucker

A PCP Characterization of AM

We introduce a 2-round stochastic constraint-satisfaction problem, and show that its approximation version is complete for (the promise version of) the complexity class $\mathsf{AM}$. This gives a `PCP characterization' of $\mathsf{AM}$ analogous to the PCP Theorem for $\mathsf{NP}$. Similar characterizations have been given for higher levels of the Polynomial Hierarchy, ... more >>>

TR10-020 | 19th February 2010
Vipul Goyal, Yuval Ishai, Mohammad Mahmoody, Amit Sahai

Interactive Locking, Zero-Knowledge PCPs, and Unconditional Cryptography

Motivated by the question of basing cryptographic protocols on stateless tamper-proof hardware tokens, we revisit the question of unconditional two-prover zero-knowledge proofs for $NP$. We show that such protocols exist in the {\em interactive PCP} model of Kalai and Raz (ICALP '08), where one of the provers is replaced by ... more >>>

TR10-021 | 21st February 2010
Pavel Hrubes, Avi Wigderson, Amir Yehudayoff

Non-commutative circuits and the sum-of-squares problem

We initiate a direction for proving lower bounds on the size of non-commutative arithmetic circuits. This direction is based on a connection between lower bounds on the size of \emph{non-commutative} arithmetic circuits and a problem about \emph{commutative} degree four polynomials, the classical sum-of-squares problem: find the smallest $n$ such that ... more >>>

TR10-022 | 23rd February 2010
Vitaly Feldman, Homin Lee, Rocco Servedio

Lower Bounds and Hardness Amplification for Learning Shallow Monotone Formulas

Much work has been done on learning various classes of ``simple'' monotone functions under the uniform distribution. In this paper we give the first unconditional lower bounds for learning problems of this sort by showing that polynomial-time algorithms cannot learn constant-depth monotone Boolean formulas under the uniform distribution in the ... more >>>

TR10-023 | 23rd February 2010
Adam Klivans, Homin Lee, Andrew Wan

Mansour’s Conjecture is True for Random DNF Formulas

Revisions: 3

In 1994, Y. Mansour conjectured that for every DNF formula on $n$ variables with $t$ terms there exists a polynomial $p$ with $t^{O(\log (1/\epsilon))}$ non-zero coefficients such that $\E_{x \in \{0,1\}}[(p(x)-f(x))^2] \leq \epsilon$. We make the first progress on this conjecture and show that it is true for several natural ... more >>>

TR10-024 | 21st February 2010
Henning Wunderlich, Stefan Arnold

On a singular value method in quantum communication complexity

Comments: 1

We introduce a new lower bound method for bounded-error quantum communication complexity,
the \emph{singular value method (svm)}, based on sums of squared singular values of the
communication matrix, and we compare it with existing methods.

The first finding is a constant factor improvement of lower bounds based on the
spectral ... more >>>

TR10-025 | 24th February 2010
Alexander A. Sherstov

Optimal bounds for sign-representing the intersection of two halfspaces by polynomials

The threshold degree of a function
$f\colon\{0,1\}^n\to\{-1,+1\}$ is the least degree of a
real polynomial $p$ with $f(x)\equiv\mathrm{sgn}\; p(x).$ We
prove that the intersection of two halfspaces on
$\{0,1\}^n$ has threshold degree $\Omega(n),$ which
matches the trivial upper bound and completely answers
a question due to Klivans (2002). The best ... more >>>

TR10-026 | 25th February 2010
Hao Huang, Benny Sudakov

A counterexample to the Alon-Saks-Seymour conjecture and related problems

Consider a graph obtained by taking edge disjoint union of $k$ complete bipartite graphs.
Alon, Saks and Seymour conjectured that such graph has chromatic number at most $k+1$.
This well known conjecture remained open for almost twenty years.
In this paper, we construct a counterexample to this
conjecture and discuss ... more >>>

TR10-027 | 28th February 2010
Arnab Bhattacharyya, Eldar Fischer, Ronitt Rubinfeld, Paul Valiant

Testing monotonicity of distributions over general partial orders

We investigate the number of samples required for testing the monotonicity of a distribution with respect to an arbitrary underlying partially ordered set. Our first result is a nearly linear lower bound for the sample complexity of testing monotonicity with respect to the poset consisting of a directed perfect matching. ... more >>>

TR10-028 | 4th March 2010
Miklos Ajtai

Oblivious RAMs without Cryptographic Assumptions

Revisions: 1

Abstract. We show that oblivious on-line simulation with only
polylogarithmic increase in the time and space requirements is possible
on a probabilistic (coin flipping) RAM without using any cryptographic
assumptions. The simulation will fail with a negligible probability.
If $n$ memory locations are used, then the probability of failure is ... more >>>

TR10-029 | 3rd March 2010
Alexandra Kolla

Spectral Algorithms for Unique Games

We present a new algorithm for Unique Games which is based on purely {\em spectral} techniques, in contrast to previous
work in the area, which relies heavily on semidefinite programming (SDP). Given a highly satisfiable instance of Unique Games, our algorithm is able to recover a good assignment.
The approximation ... more >>>

TR10-030 | 18th February 2010
Airat Khasianov

Stronger Lower Bounds on Quantum OBDD for the Hidden Subgroup Problem

Revisions: 2

We consider the \emph{Hidden Subgroup} in the context of quantum \emph{Ordered Binary Decision Diagrams}.
We show several lower bounds for this function.
In this paper we also consider a slightly more general definition of the
hidden subgroup problem (in contrast to that in \cite{khashsp1}). It turns out that ... more >>>

TR10-031 | 4th March 2010
Christian Glaßer, Christian Reitwießner, Heinz Schmitz, Maximilian Witek

Hardness and Approximability in Multi-Objective Optimization

We systematically study the hardness and the approximability of combinatorial multi-objective NP optimization problems (multi-objective problems, for short).

We define solution notions that precisely capture the typical algorithmic tasks in multi-objective optimization. These notions inherit polynomial-time Turing reducibility from multivalued functions, which allows us to compare the solution notions and ... more >>>

TR10-032 | 19th January 2010
Jack H. Lutz, Brad Shutters

Approximate Self-Assembly of the Sierpinski Triangle

The Tile Assembly Model is a Turing universal model that Winfree introduced in order to study the nanoscale self-assembly of complex (typically aperiodic) DNA crystals. Winfree exhibited a self-assembly that tiles the first quadrant of the Cartesian plane with specially labeled tiles appearing at exactly the positions of points in ... more >>>

TR10-033 | 6th March 2010
Shachar Lovett, Partha Mukhopadhyay, Amir Shpilka

Pseudorandom generators for $\mathrm{CC}_0[p]$ and the Fourier spectrum of low-degree polynomials over finite fields

In this paper we give the first construction of a pseudorandom generator, with seed length $O(\log n)$, for $\mathrm{CC}_0[p]$, the class of constant-depth circuits with unbounded fan-in $\mathrm{MOD}_p$ gates, for some prime $p$. More accurately, the seed length of our generator is $O(\log n)$ for any constant error $\epsilon>0$. In ... more >>>

TR10-034 | 7th March 2010
Luca Trevisan

The Program-Enumeration Bottleneck in Average-Case Complexity Theory

Three fundamental results of Levin involve algorithms or reductions
whose running time is exponential in the length of certain programs. We study the
question of whether such dependency can be made polynomial.

(1) Levin's ``optimal search algorithm'' performs at most a constant factor more slowly
than any other fixed ... more >>>

TR10-035 | 7th March 2010
Mark Braverman, Anup Rao, Ran Raz, Amir Yehudayoff

Pseudorandom Generators for Regular Branching Programs

We give new pseudorandom generators for \emph{regular} read-once branching programs of small width.
A branching program is regular if the in-degree of every vertex in it is (0 or) $2$.
For every width $d$ and length $n$,
our pseudorandom generator uses a seed of length $O((\log d + \log\log n ... more >>>

TR10-036 | 8th March 2010
Amir Shpilka, Ilya Volkovich

On the Relation between Polynomial Identity Testing and Finding Variable Disjoint Factors

We say that a polynomial $f(x_1,\ldots,x_n)$ is {\em indecomposable} if it cannot be written as a product of two polynomials that are defined over disjoint sets of variables. The {\em polynomial decomposition} problem is defined to be the task of finding the indecomposable factors of a given polynomial. Note that ... more >>>

TR10-037 | 8th March 2010
Boaz Barak, Guy Kindler, Ronen Shaltiel, Benny Sudakov, Avi Wigderson

Simulating Independence: New Constructions of Condensers, Ramsey Graphs, Dispersers, and Extractors

We present new explicit constructions of *deterministic* randomness extractors, dispersers and related objects. We say that a
distribution $X$ on binary strings of length $n$ is a
$\delta$-source if $X$ assigns probability at most $2^{-\delta n}$
to any string of length $n$. For every $\delta>0$ we construct the
following poly($n$)-time ... more >>>

TR10-038 | 10th March 2010
Dieter van Melkebeek, Holger Dell

Satisfiability Allows No Nontrivial Sparsification Unless The Polynomial-Time Hierarchy Collapses

Revisions: 1

Consider the following two-player communication process to decide a language $L$: The first player holds the entire input $x$ but is polynomially bounded; the second player is computationally unbounded but does not know any part of $x$; their goal is to cooperatively decide whether $x$ belongs to $L$ at small ... more >>>

TR10-039 | 10th March 2010
Gil Cohen, Amir Shpilka

On the degree of symmetric functions on the Boolean cube

Comments: 1

In this paper we study the degree of non-constant symmetric functions $f:\{0,1\}^n \to \{0,1,\ldots,c\}$, where $c\in
\mathbb{N}$, when represented as polynomials over the real numbers. We show that as long as $c < n$ it holds that deg$(f)=\Omega(n)$. As we can have deg$(f)=1$ when $c=n$, our
result shows a surprising ... more >>>

TR10-040 | 10th March 2010
Pavel Hrubes, Avi Wigderson, Amir Yehudayoff

Relationless completeness and separations

This paper extends Valiant's work on $\vp$ and $\vnp$ to the settings in which variables are not multiplicatively commutative and/or associative. Our main result is a theory of completeness for these algebraic worlds.
We define analogs of Valiant's classes $\vp$ and $\vnp$, as well as of the polynomials permanent ... more >>>

TR10-041 | 11th March 2010
Sanjeev Arora, Russell Impagliazzo, William Matthews, David Steurer

Improved Algorithms for Unique Games via Divide and Conquer

We present two new approximation algorithms for Unique Games. The first generalizes the results of Arora, Khot, Kolla, Steurer, Tulsiani, and Vishnoi who give polynomial time approximation algorithms for graphs with high conductance. We give a polynomial time algorithm assuming only good local conductance, i.e. high conductance for small subgraphs. ... more >>>

TR10-042 | 12th March 2010
Thomas Watson

Relativized Worlds Without Worst-Case to Average-Case Reductions for NP

Revisions: 3

We prove that relative to an oracle, there is no worst-case to errorless-average-case reduction for $\NP$. This result is the first progress on an open problem posed by Impagliazzo in 1995, namely to construct an oracle relative to which $\NP$ is worst-case hard but errorless-average-case easy. We also handle classes ... more >>>

TR10-043 | 5th March 2010
Johannes Köbler, Sebastian Kuhnert, Bastian Laubner, Oleg Verbitsky

Interval Graphs: Canonical Representation in Logspace

Revisions: 1

We present a logspace algorithm for computing a canonical interval representation and a canonical labeling of interval graphs. As a consequence, the isomorphism and automorphism problems for interval graphs are solvable in logspace.

more >>>

TR10-044 | 12th March 2010
Eli Ben-Sasson, Swastik Kopparty

Affine Dispersers from Subspace Polynomials

{\em Dispersers} and {\em extractors} for affine sources of dimension $d$ in $\mathbb F_p^n$ --- where $\mathbb F_p$ denotes the finite field of prime size $p$ --- are functions $f: \mathbb F_p^n \rightarrow \mathbb F_p$ that behave pseudorandomly when their domain is restricted to any particular affine space $S \subseteq ... more >>>

TR10-045 | 15th March 2010
Jakob Nordström

On the Relative Strength of Pebbling and Resolution

Revisions: 1

The last decade has seen a revival of interest in pebble games in the
context of proof complexity. Pebbling has proven to be a useful tool
for studying resolution-based proof systems when comparing the
strength of different subsystems, showing bounds on proof space, and
establishing size-space trade-offs. The typical approach ... more >>>

TR10-046 | 22nd March 2010
Ján Pich

Nisan-Wigderson generators in proof systems with forms of interpolation

We prove that the Nisan-Wigderson generators based on computationally hard functions and suitable matrices are hard for propositional proof systems that admit feasible interpolation.

more >>>

TR10-047 | 23rd March 2010
Avraham Ben-Aroya, Klim Efremenko, Amnon Ta-Shma

Local list decoding with a constant number of queries

Revisions: 1

Recently Efremenko showed locally-decodable codes of sub-exponential
length. That result showed that these codes can handle up to
$\frac{1}{3} $ fraction of errors. In this paper we show that the
same codes can be locally unique-decoded from error rate
$\half-\alpha$ for any $\alpha>0$ and locally list-decoded from
error rate $1-\alpha$ ... more >>>

TR10-048 | 24th March 2010
David García Soriano, Arie Matsliah, Sourav Chakraborty, Jop Briet

Monotonicity Testing and Shortest-Path Routing on the Cube

We study the problem of monotonicity testing over the hypercube. As
previously observed in several works, a positive answer to a natural question about routing
properties of the hypercube network would imply the existence of efficient
monotonicity testers. In particular, if any $\ell$ disjoint source-sink pairs
on the directed hypercube ... more >>>

TR10-049 | 24th March 2010
Alexey Pospelov

Bounds for Bilinear Complexity of Noncommutative Group Algebras

Revisions: 1 , Comments: 1

We study the complexity of multiplication in noncommutative group algebras which is closely related to the complexity of matrix multiplication. We characterize such semisimple group algebras of the minimal bilinear complexity and show nontrivial lower bounds for the rest of the group algebras. These lower bounds are built on the ... more >>>

TR10-050 | 25th March 2010
Samir Datta, Prajakta Nimbhorkar, Thomas Thierauf, Fabian Wagner

Graph Isomorphism for $K_{3,3}$-free and $K_5$-free graphs is in Log-space

Graph isomorphism is an important and widely studied computational problem, with
a yet unsettled complexity.
However, the exact complexity is known for isomorphism of various classes of
graphs. Recently [DLN$^+$09] proved that planar graph isomorphism is complete for log-space.
We extend this result of [DLN$^+$09] further
to the ... more >>>

TR10-051 | 26th March 2010
Madhu Sudan

Invariance in Property Testing

Property testing considers the task of testing rapidly (in particular, with very few samples into the data), if some massive data satisfies some given property, or is far from satisfying the property. For ``global properties'', i.e., properties that really depend somewhat on every piece of the data, one could ask ... more >>>

TR10-052 | 8th March 2010
Melanie Winkler, Berthold Vöcking, Sascha Geulen

Regret Minimization for Online Buffering Problems Using the Weighted Majority Algorithm

Suppose a decision maker has to purchase a commodity over time with
varying prices and demands. In particular, the price per unit might
depend on the amount purchased and this price function might vary from
step to step. The decision maker has a buffer of bounded size for
storing units ... more >>>

TR10-053 | 28th March 2010
Dana Moshkovitz, Subhash Khot

Hardness of Approximately Solving Linear Equations Over Reals

Comments: 1

In this paper, we consider the problem of approximately solving a
system of homogeneous linear equations over reals, where each
equation contains at most three variables.

Since the all-zero assignment always satisfies all the equations
exactly, we restrict the assignments to be ``non-trivial". Here is
an informal statement of our ... more >>>

TR10-054 | 30th March 2010
Jan Krajicek

On the proof complexity of the Nisan-Wigderson generator based on a hard $NP \cap coNP$ function

Let $g$ be a map defined as the Nisan-Wigderson generator
but based on an $NP \cap coNP$-function $f$. Any string $b$ outside the range of
$g$ determines a propositional tautology $\tau(g)_b$ expressing this
fact. Razborov \cite{Raz03} has conjectured that if $f$ is hard on average for
P/poly then these ... more >>>

TR10-055 | 31st March 2010
Eric Allender

Avoiding Simplicity is Complex

Revisions: 2

It is a trivial observation that every decidable set has strings of length $n$ with Kolmogorov complexity $\log n + O(1)$ if it has any strings of length $n$ at all. Things become much more interesting when one asks whether a similar property holds when one
considers *resource-bounded* Kolmogorov complexity. ... more >>>

TR10-056 | 1st April 2010
Kord Eickmeyer, Martin Grohe

Randomisation and Derandomisation in Descriptive Complexity Theory

Revisions: 1

We study probabilistic complexity classes and questions of derandomisation from a logical point of view. For each logic $\mathcal{L}$ we introduce a new logic $\mathsf{BP}\mathcal{L}$, bounded error probabilistic $\mathcal{L}$, which is defined from $\mathcal{L}$ in a similar way as the
complexity class $\mathsf{BPP}$, bounded error probabilistic polynomial time, is defined ... more >>>

TR10-057 | 1st April 2010
Scott Aaronson, Andrew Drucker

A Full Characterization of Quantum Advice

Revisions: 3

We prove the following surprising result: given any quantum state rho on n qubits, there exists a local Hamiltonian H on poly(n) qubits (e.g., a sum of two-qubit interactions), such that any ground state of H can be used to simulate rho on all quantum circuits of fixed polynomial size. ... more >>>

TR10-058 | 7th April 2010
Oded Goldreich, Tali Kaufman

Proximity Oblivious Testing and the Role of Invariances

Revisions: 1

We present a general notion of properties that
are characterized by local conditions that are invariant
under a sufficiently rich class of symmetries.
Our framework generalizes two popular models of
testing graph properties as well as the algebraic
invariances studied by Kaufman and Sudan (STOC'08).

We show that, in the ... more >>>

TR10-059 | 8th April 2010
Olaf Beyersdorff, Nicola Galesi, Massimo Lauria

Hardness of Parameterized Resolution

Parameterized Resolution and, moreover, a general framework for parameterized proof complexity was introduced by Dantchev, Martin, and Szeider (FOCS'07). In that paper, Dantchev et al. show a complexity gap in tree-like Parameterized Resolution for propositional formulas arising from translations of first-order principles.
We broadly investigate Parameterized Resolution obtaining the following ... more >>>

TR10-060 | 5th April 2010
Dmitry Gavinsky, Alexander A. Sherstov

A Separation of NP and coNP in Multiparty Communication Complexity

We prove that NP$\ne$coNP and coNP$\nsubseteq$MA in the number-on-forehead model of multiparty communication complexity for up to $k=(1-\epsilon)\log n$ players, where $\epsilon>0$ is any constant. Specifically, we construct a function $F:(\zoon)^k\to\zoo$ with co-nondeterministic
complexity $O(\log n)$ and Merlin-Arthur
complexity $n^{\Omega(1)}$.
The problem was open for $k\geq3$.

more >>>

TR10-061 | 10th April 2010
Oded Goldreich

On Testing Computability by Small Width OBDDs

Revisions: 2

We take another step in the study of the testability
of small-width OBDDs, initiated by Ron and Tsur (Random'09).
That is, we consider algorithms that,
given oracle access to a function $f:\{0,1\}^n\to\{0,1\}$,
need to determine whether $f$ can be implemented
by some restricted class of OBDDs or is far from
more >>>

TR10-062 | 7th April 2010
Michael Elberfeld, Andreas Jakoby, Till Tantau

Logspace Versions of the Theorems of Bodlaender and Courcelle

Bodlaender's Theorem states that for every $k$ there is a linear-time algorithm that decides whether an input graph has tree width~$k$ and, if so, computes a width-$k$ tree composition. Courcelle's Theorem builds on Bodlaender's Theorem and states that for every monadic second-order formula $\phi$ and for
every $k$ there is ... more >>>

TR10-063 | 12th April 2010
Venkatesan Guruswami, Yuan Zhou

Tight Bounds on the Approximability of Almost-satisfiable Horn SAT and Exact Hitting Set}

Revisions: 1

We study the approximability of two natural Boolean constraint satisfaction problems: Horn satisfiability and exact hitting set. Under the Unique Games conjecture, we prove the following optimal inapproximability and approximability results for finding an assignment satisfying as many constraints as possible given a {\em
near-satisfiable} instance.

\item ... more >>>

TR10-064 | 13th April 2010
Xin Li

A New Approach to Affine Extractors and Dispersers

We study the problem of constructing affine extractors over $\mathsf{GF(2)}$. Previously the only known construction that can handle sources with arbitrarily linear entropy is due to Bourgain (and a slight modification by Yehudayoff), which relies heavily on the technique of Van der Corput differencing and a careful choice of a ... more >>>

TR10-065 | 13th April 2010
Tali Kaufman, Shachar Lovett

Testing of exponentially large codes, by a new extension to Weil bound for character sums

Revisions: 1

In this work we consider linear codes which are locally testable
in a sublinear number of queries. We give the first general family
of locally testable codes of exponential size. Previous results of
this form were known only for codes of quasi-polynomial size (e.g.
Reed-Muller codes). We accomplish this by ... more >>>

TR10-066 | 14th April 2010
Sanjeev Arora, Rong Ge

Learning Parities with Structured Noise

Revisions: 1

In the {\em learning parities with noise} problem ---well-studied in learning theory and cryptography--- we
have access to an oracle that, each time we press a button,
returns a random vector $ a \in \GF(2)^n$ together with a bit $b \in \GF(2)$ that was computed as
$a\cdot u +\eta$, where ... more >>>

TR10-067 | 14th April 2010
Sourav Chakraborty, Eldar Fischer, Arie Matsliah

Query Complexity Lower Bounds for Reconstruction of Codes

We investigate the problem of {\em local reconstruction}, as defined by Saks and Seshadhri (2008), in the context of error correcting codes.

The first problem we address is that of {\em message reconstruction}, where given oracle access to a corrupted encoding $w \in \zo^n$ of some message $x \in \zo^k$ ... more >>>

TR10-068 | 15th April 2010
Shir Ben-Israel, Eli Ben-Sasson, David Karger

Breaking local symmetries can dramatically reduce the length of propositional refutations

This paper shows that the use of ``local symmetry breaking'' can dramatically reduce the length of propositional refutations. For each of the three propositional proof systems known as (i) treelike resolution, (ii) resolution, and (iii) k-DNF resolution, we describe families of unsatisfiable formulas in conjunctive normal form (CNF) that are ... more >>>

TR10-069 | 17th April 2010
Eric Allender, Vikraman Arvind, Fengming Wang

Uniform Derandomization from Pathetic Lower Bounds

Revisions: 1 , Comments: 1

A recurring theme in the literature on derandomization is that probabilistic
algorithms can be simulated quickly by deterministic algorithms, if one can obtain *impressive* (i.e., superpolynomial, or even nearly-exponential) circuit size lower bounds for certain problems. In contrast to what is
needed for derandomization, existing lower bounds seem rather pathetic ... more >>>

TR10-070 | 17th April 2010
Eric Allender, Klaus-Joern Lange

Symmetry Coincides with Nondeterminism for Time-Bounded Auxiliary Pushdown Automata

We show that every language accepted by a nondeterministic auxiliary pushdown automaton in polynomial time (that is, every language in SAC$^1$ = LogCFL) can be accepted by a symmetric auxiliary pushdown automaton in polynomial time.

more >>>

TR10-071 | 19th April 2010
Rahul Jain, Ashwin Nayak

The space complexity of recognizing well-parenthesized expressions

Revisions: 4

We show an Omega(sqrt(n)/T^3) lower bound for the space required by any
unidirectional constant-error randomized T-pass streaming algorithm that recognizes whether an expression over two types of parenthesis is well-parenthesized. This proves a conjecture due to Magniez, Mathieu, and Nayak
(2009) and rigorously establishes the peculiar power of bi-directional streams ... more >>>

TR10-072 | 19th April 2010
Russell Impagliazzo, Valentine Kabanets

Constructive Proofs of Concentration Bounds

We give a simple combinatorial proof of the Chernoff-Hoeffding concentration bound~\cite{Chernoff, Hof63}, which says that the sum of independent $\{0,1\}$-valued random variables is highly concentrated around the expected value. Unlike the standard proofs,
our proof does not use the method of higher moments, but rather uses a simple ... more >>>

TR10-073 | 21st April 2010
Neeraj Kayal

Algorithms for Arithmetic Circuits

Given a multivariate polynomial f(x) in F[x] as an arithmetic circuit we would like to efficiently determine:

(i) [Identity Testing.] Is f(x) identically zero?

(ii) [Degree Computation.] Is the degree of the
polynomial f(x) at most a given integer d.

(iii) [Polynomial Equivalence.] Upto an ... more >>>

TR10-074 | 20th April 2010
Parikshit Gopalan, Rocco Servedio

Learning and Lower Bounds for AC$^0$ with Threshold Gates

In 2002 Jackson et al. [JKS02] asked whether AC0 circuits augmented with a threshold gate at the output can be efficiently learned from uniform random examples. We answer this question affirmatively by showing that such circuits have fairly strong Fourier concentration; hence the low-degree algorithm of Linial, Mansour and Nisan ... more >>>

TR10-075 | 22nd April 2010
Ben Reichardt

Least span program witness size equals the general adversary lower bound on quantum query complexity

Span programs form a linear-algebraic model of computation, with span program "size" used in proving classical lower bounds. Quantum query complexity is a coherent generalization, for quantum algorithms, of classical decision-tree complexity. It is bounded below by a semi-definite program (SDP) known as the general adversary bound. We connect these ... 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 >>>

TR10-077 | 26th April 2010
Venkatesan Guruswami, Adam Smith

Codes for Computationally Simple Channels: Explicit Constructions with Optimal Rate

In this paper, we consider coding schemes for computationally bounded channels, which can introduce an arbitrary set of errors as long as (a) the fraction of errors is bounded with high probability by a parameter p and (b) the process which adds the errors can be described by a sufficiently ... more >>>

TR10-078 | 27th April 2010
Holger Dell, Thore Husfeldt, Martin Wahlén

Exponential Time Complexity of the Permanent and the Tutte Polynomial

Revisions: 1

The Exponential Time Hypothesis (ETH) says that deciding the satisfiability of $n$-variable 3-CNF formulas requires time $\exp(\Omega(n))$. We relax this hypothesis by introducing its counting version #ETH, namely that every algorithm that counts the satisfying assignments requires time $\exp(\Omega(n))$. We transfer the sparsification lemma for $d$-CNF formulas to the counting ... more >>>

TR10-079 | 28th April 2010
Samir Datta, Raghav Kulkarni, Raghunath Tewari, Vinodchandran Variyam

Space Complexity of Perfect Matching in Bounded Genus Bipartite Graphs

We investigate the space complexity of certain perfect matching
problems over bipartite graphs embedded on surfaces of constant genus
(orientable or non-orientable). We show that the problems of deciding
whether such graphs have (1) a perfect matching or not and (2) a
unique perfect matching or not, are in the ... more >>>

TR10-080 | 5th May 2010
Andrew Drucker

Improved Direct Product Theorems for Randomized Query Complexity

Revisions: 1

The direct product problem is a fundamental question in complexity theory which seeks to understand how the difficulty of computing a function on each of $k$ independent inputs scales with $k$.
We prove the following direct product theorem (DPT) for query complexity: if every $T$-query algorithm
has success probability at ... more >>>

TR10-081 | 10th May 2010
Olaf Beyersdorff, Nicola Galesi, Massimo Lauria

A Lower Bound for the Pigeonhole Principle in Tree-like Resolution by Asymmetric Prover-Delayer Games

In this note we show that the asymmetric Prover-Delayer game developed by Beyersdorff, Galesi, and Lauria (ECCC TR10-059) for Parameterized Resolution is also applicable to other tree-like proof systems. In particular, we use this asymmetric Prover-Delayer game to show a lower bound of the form $2^{\Omega(n\log n)}$ for the pigeonhole ... more >>>

TR10-082 | 11th May 2010
Oded Goldreich

Introduction to Testing Graph Properties

The aim of this article is to introduce the reader to the study
of testing graph properties, while focusing on the main models
and issues involved. No attempt is made to provide a
comprehensive survey of this study, and specific results
are often mentioned merely as illustrations of general ... more >>>

TR10-083 | 13th May 2010
Mark Braverman, Anup Rao

Efficient Communication Using Partial Information

Revisions: 1

We show how to efficiently simulate the sending of a message M to a receiver who has partial information about the message, so that the expected number of bits communicated in the simulation is close to the amount of additional information that the message reveals to the receiver.

We ... more >>>

TR10-084 | 14th May 2010
Maurice Jansen, Youming Qiao, Jayalal Sarma

Deterministic Identity Testing of Read-Once Algebraic Branching Programs

An algebraic branching program (ABP) is given by a directed acyclic graph with source and sink vertices $s$ and $t$, respectively, and where edges are labeled by variables or field constants. An ABP computes the sum of weights of all directed paths from $s$ to $t$, where the weight of ... more >>>

TR10-085 | 20th May 2010
Eli Ben-Sasson, Jan Johannsen

Lower bounds for width-restricted clause learning on small width formulas

It has been observed empirically that clause learning does not significantly improve the performance of a SAT solver when restricted
to learning clauses of small width only. This experience is supported by lower bound theorems. It is shown that lower bounds on the runtime of width-restricted clause learning follow from ... more >>>

TR10-086 | 17th May 2010
Henning Wunderlich

On a Theorem of Razborov

In an unpublished Russian manuscript Razborov proved that a matrix family with high
rigidity over a finite field would yield a language outside the polynomial hierarchy
in communication complexity.

We present an alternative proof that strengthens the original result in several ways.
In particular, we replace rigidity by the strictly ... more >>>

TR10-087 | 17th May 2010
Shachar Lovett, Ely Porat

A lower bound for dynamic approximate membership data structures

An approximate membership data structure is a randomized data
structure for representing a set which supports membership
queries. It allows for a small false positive error rate but has
no false negative errors. Such data structures were first
introduced by Bloom in the 1970's, and have since had numerous
applications, ... more >>>

TR10-088 | 17th May 2010
Jiri Sima, Stanislav Zak

A Polynomial Time Construction of a Hitting Set for Read-Once Branching Programs of Width 3

Revisions: 2 , Comments: 3

The relationship between deterministic and probabilistic computations is one of the central issues in complexity theory. This problem can be tackled by constructing polynomial time hitting set generators which, however, belongs to the hardest problems in computer science even for severely restricted computational models. In our work, we consider read-once ... more >>>

TR10-089 | 26th May 2010
Iftach Haitner, Omer Reingold, Salil Vadhan

Efficiency Improvements in Constructing Pseudorandom Generators from One-way Functions

We give a new construction of pseudorandom generators from any one-way function. The construction achieves better parameters and is simpler than that given in the seminal work of Haastad, Impagliazzo, Levin and Luby [SICOMP '99]. The key to our construction is a new notion of next-block pseudoentropy, which is inspired ... more >>>

TR10-090 | 14th May 2010
Nikolay Vereshchagin

{Algorithmic Minimal Sufficient Statistics: a New Definition

We express some criticism about the definition of an algorithmic sufficient statistic and, in particular, of an algorithmic minimal sufficient statistic. We propose another definition, which has better properties.

more >>>

TR10-091 | 14th May 2010
Nikolay Vereshchagin

An Encoding Invariant Version of Polynomial Time Computable Distributions

When we represent a decision problem,like CIRCUIT-SAT, as a language over the binary alphabet,
we usually do not specify how to encode instances by binary strings.
This relies on the empirical observation that the truth of a statement of the form ``CIRCUIT-SAT belongs to a complexity class $C$''
more >>>

TR10-092 | 22nd May 2010
Charanjit Jutla, Arnab Roy

A Completeness Theorem for Pseudo-Linear Functions with Applications to UC Security

Revisions: 1 , Comments: 1

We consider multivariate pseudo-linear functions
over finite fields of characteristic two. A pseudo-linear polynomial
is a sum of guarded linear-terms, where a guarded linear-term is a product of one or more linear-guards
and a single linear term, and each linear-guard is
again a linear term but raised ... more >>>

TR10-093 | 3rd June 2010
Sourav Chakraborty, David García Soriano, Arie Matsliah

Nearly Tight Bounds for Testing Function Isomorphism

In this paper we study the problem of testing structural equivalence (isomorphism) between a pair of Boolean
functions $f,g:\zo^n \to \zo$. Our main focus is on the most studied case, where one of the functions is given (explicitly), and the other function can be queried.

We prove that for every ... more >>>

TR10-094 | 17th May 2010
Ajesh Babu, Nutan Limaye, Girish Varma

Streaming algorithms for some problems in log-space.

In this paper, we give streaming algorithms for some problems which are known to be in deterministic log-space, when the number of passes made on the input is unbounded. If the input data is massive,
the conventional deterministic log-space algorithms may not run efficiently. We study the complexity of the ... more >>>

TR10-095 | 11th June 2010
Masaki Yamamoto

A combinatorial analysis for the critical clause tree

In [FOCS1998],
Paturi, Pudl\'ak, Saks, and Zane proposed a simple randomized algorithm
for finding a satisfying assignment of a $k$-CNF formula.
The main lemma of the paper is as follows:
Given a satisfiable $k$-CNF formula that
has a $d$-isolated satisfying assignment $z$,
the randomized algorithm finds $z$
with probability at ... more >>>

TR10-096 | 16th June 2010
Dana Moshkovitz

An Alternative Proof of The Schwartz-Zippel Lemma

Revisions: 1

We show a non-inductive proof of the Schwartz-Zippel lemma. The lemma bounds the number of zeros of a multivariate low degree polynomial over a finite field.

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 >>>

TR10-098 | 17th June 2010
Daniel Kane, Jelani Nelson

A Derandomized Sparse Johnson-Lindenstrauss Transform

Revisions: 2

Recent work of [Dasgupta-Kumar-Sarl\'{o}s, STOC 2010] gave a sparse Johnson-Lindenstrauss transform and left as a main open question whether their construction could be efficiently derandomized. We answer their question affirmatively by giving an alternative proof of their result requiring only bounded independence hash functions. Furthermore, the sparsity bound obtained in ... more >>>

TR10-099 | 20th June 2010
T.C. Vijayaraghavan

A Note on Closure Properties of ModL

Recently in [Vij09, Corollary 3.7] the complexity class ModL has been shown to be closed under complement assuming NL = UL. In this note we continue to show many other closure properties of ModL which include the following.

1. ModL is closed under $\leq ^L_m$ reduction, $\vee$(join) and $\leq ^{UL}_m$ ... more >>>

TR10-100 | 25th June 2010
Amit Chakrabarti

A Note on Randomized Streaming Space Bounds for the Longest Increasing Subsequence Problem

The deterministic space complexity of approximating the length of the longest increasing subsequence of
a stream of $N$ integers is known to be $\widetilde{\Theta}(\sqrt N)$. However, the randomized
complexity is wide open. We show that the technique used in earlier work to establish the $\Omega(\sqrt
N)$ deterministic lower bound fails ... more >>>

TR10-101 | 25th June 2010
Samir Datta, Meena Mahajan, Raghavendra Rao B V, Michael Thomas, Heribert Vollmer

Counting Classes and the Fine Structure between NC$^1$ and L.

The class NC$^1$ of problems solvable by bounded fan-in circuit families of logarithmic depth is known to be contained in logarithmic space L, but not much about the converse is known. In this paper we examine the structure of classes in between NC$^1$ and L based on counting functions or, ... more >>>

TR10-102 | 12th May 2010
Per Kristian Lehre, Carsten Witt

Black-Box Search by Unbiased Variation

Revisions: 1

The complexity theory for black-box algorithms, introduced by
Droste et al. (2006), describes common limits on the efficiency of
a broad class of randomised search heuristics. There is an
obvious trade-off between the generality of the black-box model
and the strength of the bounds that can be proven in such ... more >>>

TR10-103 | 28th June 2010
Andreas Krebs, Nutan Limaye, Meena Mahajan

Counting paths in VPA is complete for \#NC$^1$

We give a \#NC$^1$ upper bound for the problem of counting accepting paths in any fixed visibly pushdown automaton. Our algorithm involves a non-trivial adaptation of the arithmetic formula evaluation algorithm of Buss, Cook, Gupta, Ramachandran (BCGR: SICOMP 21(4), 1992). We also show that the problem is \#NC$^1$ hard. Our ... more >>>

TR10-104 | 29th June 2010
Paul Beame, Widad Machmouchi

Making RAMs Oblivious Requires Superlogarithmic Overhead

Revisions: 3 , Comments: 1

We prove a time-space tradeoff lower bound of $T =
\Omega\left(n\log(\frac{n}{S}) \log \log(\frac{n}{S})\right) $ for
randomized oblivious branching programs to compute $1GAP$, also
known as the pointer jumping problem, a problem for which there is a
simple deterministic time $n$ and space $O(\log n)$ RAM (random
access machine) algorithm.

In ... more >>>

TR10-105 | 29th June 2010
Scott Aaronson, Dieter van Melkebeek

A note on circuit lower bounds from derandomization

We present an alternate proof of the result by Kabanets and Impagliazzo that derandomizing polynomial identity testing implies circuit lower bounds. Our proof is simpler, scales better, and yields a somewhat stronger result than the original argument.

more >>>

TR10-106 | 17th June 2010
Yuichi Yoshida

Optimal Constant-Time Approximation Algorithms and (Unconditional) Inapproximability Results for Every Bounded-Degree CSP

Revisions: 1

Raghavendra (STOC 2008) gave an elegant and surprising result: if Khot's Unique Games Conjecture (STOC 2002) is true, then for every constraint satisfaction problem (CSP), the best approximation ratio is attained by a certain simple semidefinite programming and a rounding scheme for it.
In this paper, we show that a ... more >>>

TR10-107 | 6th July 2010
Irit Dinur, Or Meir

Derandomized Parallel Repetition via Structured PCPs

Revisions: 3

A PCP is a proof system for NP in which the proof can be checked by a probabilistic verifier. The verifier is only allowed to read a very small portion of the proof, and in return is allowed to err with some bounded probability. The probability that the verifier accepts ... more >>>

TR10-108 | 9th July 2010
Eli Ben-Sasson, Madhu Sudan

Limits on the rate of locally testable affine-invariant codes

A linear code is said to be affine-invariant if the coordinates of the code can be viewed as a vector space and the code is invariant under an affine transformation of the coordinates. A code is said to be locally testable if proximity of a received word
to the code ... more >>>

TR10-109 | 11th July 2010
Scott Aaronson

A Counterexample to the Generalized Linial-Nisan Conjecture

In earlier work, we gave an oracle separating the relational versions of BQP and the polynomial hierarchy, and showed that an oracle separating the decision versions would follow from what we called the Generalized Linial-Nisan (GLN) Conjecture: that "almost k-wise independent" distributions are indistinguishable from the uniform distribution by constant-depth ... more >>>

TR10-110 | 14th July 2010
Ben Reichardt

Span programs and quantum query algorithms

Quantum query complexity measures the number of input bits that must be read by a quantum algorithm in order to evaluate a function. Hoyer et al. (2007) have generalized the adversary semi-definite program that lower-bounds quantum query complexity. By giving a matching algorithm, we show that the general adversary lower ... more >>>

TR10-111 | 14th July 2010
Venkatesan Guruswami, Ali Kemal Sinop

The complexity of finding independent sets in bounded degree (hyper)graphs of low chromatic number

We prove almost tight hardness results for finding independent sets in bounded degree graphs and hypergraphs that admit a good
coloring. Our specific results include the following (where $\Delta$, assumed to be a constant, is a bound on the degree, and
$n$ is the number of vertices):

... more >>>

TR10-112 | 15th July 2010
Subhash Khot, Dana Moshkovitz

NP-Hardness of Approximately Solving Linear Equations Over Reals

In this paper, we consider the problem of approximately solving a system of homogeneous linear equations over reals, where each
equation contains at most three variables.

Since the all-zero assignment always satisfies all the equations exactly, we restrict the assignments to be ``non-trivial". Here is
an informal statement of our ... more >>>

TR10-113 | 16th July 2010
Michal Koucky, Prajakta Nimbhorkar, Pavel Pudlak

Pseudorandom Generators for Group Products

We prove that the pseudorandom generator introduced in Impagliazzo et al. (1994) fools group products of a given finite group. The seed length is $O(\log n \log 1 / \epsilon)$, where $n$ is the length of the word and $\epsilon$ is the error. The result is equivalent to the statement ... more >>>

TR10-114 | 17th July 2010
Zhixiang Chen, Bin Fu

The Complexity of Testing Monomials in Multivariate Polynomials

The work in this paper is to initiate a theory of testing
monomials in multivariate polynomials. The central question is to
ask whether a polynomial represented by certain economically
compact structure has a multilinear monomial in its sum-product
expansion. The complexity aspects of this problem and its variants
are investigated ... more >>>

TR10-115 | 17th July 2010
Shachar Lovett, Emanuele Viola

Bounded-depth circuits cannot sample good codes

We study a variant of the classical circuit-lower-bound problems: proving lower bounds for sampling distributions given random bits. We prove a lower bound of $1-1/n^{\Omega(1)}$ on the statistical distance between (i) the output distribution of any small constant-depth (a.k.a.~$\mathrm{AC}^0$) circuit $f : \{0,1\}^{\mathrm{poly}(n)} \to \{0,1\}^n$, and (ii) the uniform distribution ... more >>>

TR10-116 | 21st July 2010
Arnab Bhattacharyya, Victor Chen, Madhu Sudan, Ning Xie

Testing linear-invariant non-linear properties: A short report

The rich collection of successes in property testing raises a natural question: Why are so many different properties turning out to be locally testable? Are there some broad "features" of properties that make them testable? Kaufman and Sudan (STOC 2008) proposed the study of the relationship between the invariances satisfied ... more >>>

TR10-117 | 22nd July 2010
Arkadev Chattopadhyay, Jacobo Toran, Fabian Wagner

Graph Isomorphism is not AC^0 reducible to Group Isomorphism

We give a new upper bound for the Group and Quasigroup
Isomorphism problems when the input structures
are given explicitly by multiplication tables. We show that these problems can be computed by polynomial size nondeterministic circuits of unbounded fan-in with $O(\log\log n)$ depth and $O(\log^2 n)$ nondeterministic bits, ... more >>>

TR10-118 | 27th July 2010
Maurice Jansen

Extracting Roots of Arithmetic Circuits by Adapting Numerical Methods

Revisions: 2

For two polynomials $f \in \mathbb{F}[x_1, x_2, \ldots, x_n, y]$ and $p \in \mathbb{F}[x_1, x_2, \ldots, x_n]$, we say that $p$ is a root of $f$, if $f(x_1, x_2, \ldots, x_n, p) \equiv 0$. We study the relation between the arithmetic circuit sizes of $f$ and $p$ for general circuits ... more >>>

TR10-119 | 27th July 2010
Michal Moshkovitz

Distance Estimators with Sublogarithmic Number of Queries

A distance estimator is a code together with a randomized algorithm. The algorithm approximates the distance of any word from the code by making a small number of queries to the word. One such example is the Reed-Muller code equipped with an appropriate algorithm. It has polynomial length, polylogarithmic alphabet ... more >>>

TR10-120 | 27th July 2010
Noa Eidelstein, Alex Samorodnitsky

Lower bounds for designs in symmetric spaces

A design is a finite set of points in a space on which every "simple" functions averages to its global mean. Illustrative examples of simple functions are low-degree polynomials on the Euclidean sphere or on the Hamming cube.

We prove lower bounds on designs in spaces with a large group ... more >>>

TR10-121 | 28th July 2010
Ashwin Nayak

Inverting a permutation is as hard as unordered search

Revisions: 1

We describe a reduction from the problem of unordered search(with a unique solution) to the problem of inverting a permutation. Since there is a straightforward reduction in the reverse direction, the problems are essentially equivalent.

The reduction helps us bypass the Bennett-Bernstein-Brassard-Vazirani hybrid argument (1997} and the Ambainis quantum adversary ... more >>>

TR10-122 | 18th July 2010
Zhixiang Chen, Bin Fu, Yang Liu, Robert Schweller

Algorithms for Testing Monomials in Multivariate Polynomials

This paper is our second step towards developing a theory of
testing monomials in multivariate polynomials. The central
question is to ask whether a polynomial represented by an
arithmetic circuit has some types of monomials in its sum-product
expansion. The complexity aspects of this problem and its variants
have been ... more >>>

TR10-123 | 4th August 2010
Eli Ben-Sasson

Limitation on the rate of families of locally testable codes

Revisions: 1

This paper describes recent results which revolve around the question of the rate attainable by families of error correcting codes that are locally testable. Emphasis is placed on motivating the problem of proving upper bounds on the rate of these codes and a number of interesting open questions for future ... more >>>

TR10-124 | 18th July 2010
Zhixiang Chen, Bin Fu

Approximating Multilinear Monomial Coefficients and Maximum Multilinear Monomials in Multivariate Polynomials

This paper is our third step towards developing a theory of testing monomials in multivariate polynomials and concentrates on two problems: (1) How to compute the coefficients of multilinear monomials; and (2) how to find a maximum multilinear monomial when the input is a $\Pi\Sigma\Pi$ polynomial.
We first prove ... more >>>

TR10-125 | 11th August 2010
Eli Ben-Sasson, Jakob Nordström

Understanding Space in Proof Complexity: Separations and Trade-offs via Substitutions

For current state-of-the-art satisfiability algorithms based on the DPLL procedure and clause learning, the two main bottlenecks are the amounts of time and memory used. In the field of proof complexity, these resources correspond to the length and space of resolution proofs for formulas in conjunctive normal form (CNF). There ... more >>>

TR10-126 | 12th August 2010
Thomas Watson

Query Complexity in Errorless Hardness Amplification

Revisions: 2

An errorless circuit for a boolean function is one that outputs the correct answer or ``don't know'' on each input (and never outputs the wrong answer). The goal of errorless hardness amplification is to show that if $f$ has no size $s$ errorless circuit that outputs ``don't know'' on at ... more >>>

TR10-127 | 9th August 2010
Brett Hemenway, Rafail Ostrovsky

Building Injective Trapdoor Functions From Oblivious Transfer

Revisions: 1

Injective one-way trapdoor functions are one of the most fundamental cryptographic primitives. In this work we give a novel construction of injective trapdoor functions based on oblivious transfer for long strings.

Our main result is to show that any 2-message statistically sender-private semi-honest oblivious transfer (OT) for ... more >>>

TR10-128 | 15th August 2010
Scott Aaronson

The Equivalence of Sampling and Searching

Revisions: 1

In a sampling problem, we are given an input $x\in\left\{0,1\right\} ^{n}$, and asked to sample approximately from a probability
distribution $D_{x}$ over poly(n)-bit strings. In a search problem, we are given an input
$x\in\left\{ 0,1\right\} ^{n}$, and asked to find a member of a nonempty set
$A_{x}$ with high probability. ... more >>>

TR10-129 | 16th August 2010
Jeff Kinne, Dieter van Melkebeek, Ronen Shaltiel

Pseudorandom Generators, Typically-Correct Derandomization, and Circuit Lower Bounds

The area of derandomization attempts to provide efficient deterministic simulations of randomized algorithms in various algorithmic settings. Goldreich and Wigderson introduced a notion of "typically-correct" deterministic simulations, which are allowed to err on few inputs. In this paper we further the study of typically-correct derandomization in two ways.

First, we ... more >>>

TR10-130 | 18th August 2010
Tali Kaufman, Michael Viderman

Locally Testable vs. Locally Decodable Codes

Revisions: 1

We study the relation between locally testable and locally decodable codes.
Locally testable codes (LTCs) are error-correcting codes for which membership of a given word in the code can be tested probabilistically by examining it in very few locations. Locally decodable codes (LDCs) allow to recover each message entry with ... more >>>

TR10-131 | 9th July 2010
Nathaniel Bryans, Ehsan Chiniforooshan, David Doty, Lila Kari, Shinnosuke Seki

The Power of Nondeterminism in Self-Assembly

We investigate the role of nondeterminism in Winfree's abstract Tile Assembly Model (aTAM), which was conceived to model artificial molecular self-assembling systems constructed from DNA. Designing tile systems that assemble shapes, due to the algorithmic richness of the aTAM, is a form of sophisticated "molecular programming". Of particular practical importance ... more >>>

TR10-132 | 18th August 2010
Mahdi Cheraghchi, Johan Hastad, Marcus Isaksson, Ola Svensson

Approximating Linear Threshold Predicates

We study constraint satisfaction problems on the domain $\{-1,1\}$, where the given constraints are homogeneous linear threshold predicates. That is, predicates of the form $\mathrm{sgn}(w_1 x_1 + \cdots + w_n x_n)$ for some positive integer weights $w_1, \dots, w_n$. Despite their simplicity, current techniques fall short of providing a classification ... more >>>

TR10-133 | 20th August 2010
Parikshit Gopalan, Adam Klivans, Raghu Meka

Polynomial-Time Approximation Schemes for Knapsack and Related Counting Problems using Branching Programs

We give a deterministic, polynomial-time algorithm for approximately counting the number of {0,1}-solutions to any instance of the knapsack problem. On an instance of length n with total weight W and accuracy parameter eps, our algorithm produces a (1 + eps)-multiplicative approximation in time poly(n,log W,1/eps). We also give algorithms ... more >>>

TR10-134 | 23rd August 2010
Avraham Ben-Aroya, Klim Efremenko, Amnon Ta-Shma

A Note on Amplifying the Error-Tolerance of Locally Decodable Codes

Revisions: 2

We show a generic, simple way to amplify the error-tolerance of locally decodable codes.
Specifically, we show how to transform a locally decodable code that can tolerate a constant fraction of errors
to a locally decodable code that can recover from a much higher error-rate. We also show how to ... more >>>

TR10-135 | 24th August 2010
Oded Goldreich

In a World of P=BPP

Revisions: 2

We show that proving results such as BPP=P essentially
necessitate the construction of suitable pseudorandom generators
(i.e., generators that suffice for such derandomization results).
In particular, the main incarnation of this equivalence
refers to the standard notion of uniform derandomization
and to the corresponding pseudorandom generators
(i.e., the standard uniform ... more >>>

TR10-136 | 26th August 2010
Arnab Bhattacharyya, Elena Grigorescu, Jakob Nordström, Ning Xie

Separations of Matroid Freeness Properties

Revisions: 1

Properties of Boolean functions on the hypercube that are invariant
with respect to linear transformations of the domain are among some of
the most well-studied properties in the context of property testing.
In this paper, we study a particular natural class of linear-invariant
properties, called matroid freeness properties. These properties ... more >>>

TR10-137 | 29th August 2010
Or Meir

IP = PSPACE using Error Correcting Codes

Revisions: 5

The IP theorem, which asserts that IP = PSPACE (Lund et. al., and Shamir, in J. ACM 39(4)), is one of the major achievements of complexity theory. The known proofs of the theorem are based on the arithmetization technique, which transforms a quantified Boolean formula into a related polynomial. The ... more >>>

TR10-138 | 17th September 2010
Eric Allender, Luke Friedman, William Gasarch

Exposition of the Muchnik-Positselsky Construction of a Prefix Free Entropy Function that is not Complete under Truth-Table Reductions

In this paper we give an exposition of a theorem by Muchnik and Positselsky, showing that there is a universal prefix Turing machine U, with the property that there is no truth-table reduction from the halting problem to the set {(x,i) : there is a description d of length at ... more >>>

TR10-139 | 17th September 2010
Eric Allender, Luke Friedman, William Gasarch

Limits on the Computational Power of Random Strings

Revisions: 1

Let C(x) and K(x) denote plain and prefix Kolmogorov complexity, respectively, and let R_C and R_K denote the sets of strings that are ``random'' according to these measures; both R_K and R_C are undecidable. Earlier work has shown that every set in NEXP is in NP relative to both R_K ... more >>>

TR10-140 | 17th September 2010
Amit Chakrabarti, Oded Regev

An Optimal Lower Bound on the Communication Complexity of Gap-Hamming-Distance

We prove an optimal $\Omega(n)$ lower bound on the randomized
communication complexity of the much-studied
Gap-Hamming-Distance problem. As a consequence, we
obtain essentially optimal multi-pass space lower bounds in the
data stream model for a number of fundamental problems, including
the estimation of frequency moments.

The Gap-Hamming-Distance problem is a ... more >>>

TR10-141 | 18th September 2010 (removed)
Ran Raz

A Strong Parallel Repetition Theorem for Projection Games on Expanders

Reason: This paper has been remove on the author's behalf. Please note that TR10-142 is the corrected version.

TR10-142 | 18th September 2010
Ran Raz, Ricky Rosen

A Strong Parallel Repetition Theorem for Projection Games on Expanders

The parallel repetition theorem states that for any Two
Prover Game with value at most $1-\epsilon$ (for $\epsilon<1/2$),
the value of the game repeated $n$ times in parallel is at most
$(1-\epsilon^3)^{\Omega(n/s)}$, where $s$ is the length of the
answers of the two provers. For Projection
Games, the bound on ... more >>>

TR10-143 | 19th September 2010
Bo'az Klartag, Oded Regev

Quantum One-Way Communication is Exponentially Stronger Than Classical Communication

In STOC 1999, Raz presented a (partial) function for which there is a quantum protocol
communicating only $O(\log n)$ qubits, but for which any classical (randomized, bounded-error) protocol requires $\poly(n)$ bits of communication. That quantum protocol requires two rounds of communication. Ever since Raz's paper it was open whether the ... more >>>

TR10-144 | 20th September 2010
Eli Ben-Sasson, Noga Ron-Zewi

From Affine to Two-Source Extractors via Approximate Duality

Revisions: 1

Two-source and affine extractors and dispersers are fundamental objects studied in the context of derandomization. This paper shows how to construct two-source extractors and dispersers for arbitrarily small min-entropy rate in a black-box manner from affine extractors with sufficiently good parameters. Our analysis relies on the study of approximate duality, ... more >>>

TR10-145 | 21st September 2010
Ron Rothblum

A Taxonomy of Enhanced Trapdoor Permutations

Trapdoor permutations (TDPs) are among the most widely studied
building blocks of cryptography. Despite the extensive body of
work that has been dedicated to their study, in many setting and
applications (enhanced) trapdoor permutations behave
unexpectedly. In particular, a TDP may become easy to invert when
the inverter is given ... more >>>

TR10-146 | 21st September 2010
Ron Rothblum

Homomorphic Encryption: from Private-Key to Public-Key

We show that any private-key encryption scheme that is weakly
homomorphic with respect to addition modulo 2, can be transformed
into a public-key encryption scheme. The homomorphic feature
referred to is a minimalistic one; that is, the length of a
homomorphically generated encryption should be independent of the
number of ... more >>>

TR10-147 | 22nd September 2010
Dieter van Melkebeek, Thomas Watson

Time-Space Efficient Simulations of Quantum Computations

Revisions: 1

We give two time- and space-efficient simulations of quantum computations with
intermediate measurements, one by classical randomized computations with
unbounded error and the other by quantum computations that use an arbitrary
fixed universal set of gates. Specifically, our simulations show that every
language solvable by a bounded-error quantum algorithm running ... more >>>

TR10-148 | 23rd September 2010
Swastik Kopparty, Shubhangi Saraf, Sergey Yekhanin

High-rate codes with sublinear-time decoding

Locally decodable codes are error-correcting codes that admit efficient decoding algorithms; any bit of the original message can be recovered by looking at only a small number of locations of a corrupted codeword. The tradeoff between the rate of a code and the locality/efficiency of its decoding algorithms has been ... more >>>

TR10-149 | 22nd September 2010
Boaz Barak, Zeev Dvir, Avi Wigderson, Amir Yehudayoff

Rank Bounds for Design Matrices with Applications to Combinatorial Geometry and Locally Correctable Codes

Revisions: 1

A $(q,k,t)$-design matrix is an m x n matrix whose pattern of zeros/non-zeros satisfies the following design-like condition: each row has at most $q$ non-zeros, each column has at least $k$ non-zeros and the supports of every two columns intersect in at most t rows. We prove that the rank ... more >>>

TR10-150 | 19th September 2010
Bjørn Kjos-Hanssen

A strong law of computationally weak subsets

We show that in the setting of fair-coin measure on the power set of the natural numbers, each sufficiently random set has an infinite subset that computes no random set. That is, there is an almost sure event $\mathcal A$ such that if $X\in\mathcal A$ then $X$ has an infinite ... more >>>

TR10-151 | 30th September 2010
Raghunath Tewari, Vinodchandran Variyam

Green’s Theorem and Isolation in Planar Graphs

We show a simple application of Green’s theorem from multivariable calculus to the isolation problem in planar graphs. In particular, we construct a skew-symmetric, polynomially bounded, edge weight function for a directed planar graph in logspace such that the weight of any simple cycle in the graph is non-zero with ... more >>>

TR10-152 | 6th October 2010
Alexey Pospelov

Faster Polynomial Multiplication via Discrete Fourier Transforms

We study the complexity of polynomial multiplication over arbitrary fields. We present a unified approach that generalizes all known asymptotically fastest algorithms for this problem. In particular, the well-known algorithm for multiplication of polynomials over fields supporting DFTs of large smooth orders, Schönhage-Strassen's algorithm over arbitrary fields of characteristic different ... more >>>

TR10-153 | 7th October 2010
Lorenzo Carlucci, Nicola Galesi, Massimo Lauria

Paris-Harrington tautologies

Revisions: 2

We initiate the study of the proof complexity of propositional encoding of (weak cases of) concrete independence results. In particular we study the proof complexity of Paris-Harrington's Large Ramsey Theorem. We prove a conditional lower bound in Resolution and a quasipolynomial upper bound in bounded-depth Frege.

more >>>

TR10-154 | 8th October 2010
Derrick Stolee, Vinodchandran Variyam

Space-Efficient Algorithms for Reachability in Surface-Embedded Graphs

We consider the reachability problem for a certain class of directed acyclic graphs embedded on surfaces. Let ${\cal G}(m,g)$ be the class of directed acyclic graphs with $m = m(n)$ source vertices embedded on a surface (orientable or non-orientable) of genus $g = g(n)$. We give a log-space reduction that ... more >>>

TR10-155 | 14th October 2010
Brendan Juba, Madhu Sudan

Efficient Semantic Communication via Compatible Beliefs

In previous works, Juba and Sudan (STOC 2008) and Goldreich, Juba and Sudan (ECCC TR09-075) considered the idea of "semantic communication", wherein two players, a user and a server, attempt to communicate with each other without any prior common language (or communication protocol). They showed that if communication was goal-oriented ... more >>>

TR10-156 | 24th October 2010
Victor Chen, Madhu Sudan, Ning Xie

Property Testing via Set-Theoretic Operations

Given two testable properties $\mathcal{P}_{1}$ and $\mathcal{P}_{2}$, under what conditions are the union, intersection or set-difference
of these two properties also testable?
We initiate a systematic study of these basic set-theoretic operations in the context of property
testing. As an application, we give a conceptually different proof that linearity is ... more >>>

TR10-157 | 24th October 2010
Reut Levi, Dana Ron, Ronitt Rubinfeld

Testing Properties of Collections of Distributions

Revisions: 1

We propose a framework for studying property testing of collections of distributions,
where the number of distributions in the collection is a parameter of the problem.
Previous work on property testing of distributions considered
single distributions or pairs of distributions. We suggest two models that differ
in the way the ... more >>>

TR10-158 | 31st October 2010
Shiva Kintali

Realizable Paths and the NL vs L Problem

Revisions: 2

A celebrated theorem of Savitch states that NSPACE(S) is contained DSPACE(S^2). In particular, Savitch gave a deterministic algorithm to solve ST-CONNECTIVITY (an NL-complete problem) using O(log^2{n}) space, implying NL is in DSPACE(log^2{n}). While Savitch’s theorem itself has not been improved in the last four decades, studying the space complexity of ... more >>>

TR10-159 | 28th October 2010
Graham Cormode, Justin Thaler, Ke Yi

Verifying Computations with Streaming Interactive Proofs

Applications based on outsourcing computation require guarantees to the data owner that the desired computation has been performed correctly by the service provider. Methods based on proof systems can give the data owner the necessary assurance, but previous work does not give a sufficiently scalable and practical solution, requiring a ... more >>>

TR10-160 | 28th October 2010
Zeev Dvir, Dan Gutfreund, Guy Rothblum, Salil Vadhan

On Approximating the Entropy of Polynomial Mappings

We investigate the complexity of the following computational problem:

Polynomial Entropy Approximation (PEA):
Given a low-degree polynomial mapping
$p : F^n\rightarrow F^m$, where $F$ is a finite field, approximate the output entropy
$H(p(U_n))$, where $U_n$ is the uniform distribution on $F^n$ and $H$ may be any of several entropy measures.

... more >>>

TR10-161 | 25th October 2010
Arnab Bhattacharyya, Elena Grigorescu, Asaf Shapira

A Unified Framework for Testing Linear-Invariant Properties

The study of the interplay between the testability of properties of Boolean functions and the invariances acting on their domain which preserve the property was initiated by Kaufman and Sudan (STOC 2008). Invariance with respect to F_2-linear transformations is arguably the most common symmetry exhibited by natural properties of Boolean ... more >>>

TR10-162 | 30th October 2010
Zohar Karnin

Deterministic Construction of a high dimensional $\ell_p$ section in $\ell_1^n$ for any $p<2$

For any $00$, we give an efficient
deterministic construction of a linear subspace $V \subseteq
\R^n$, of dimension $(1-\epsilon)n$ in which the $\ell_p$ and
$\ell_r$ norms are the same up to a multiplicative factor of
$\poly(\epsilon^{-1})$ (after the correct normalization). As a
corollary we get a deterministic compressed sensing algorithm
more >>>

TR10-163 | 3rd November 2010
Harry Buhrman, Leen Torenvliet, Falk Unger, Nikolay Vereshchagin

Sparse Selfreducible Sets and Nonuniform Lower Bounds

It is well-known that the class of sets that can be computed by polynomial size circuits is equal to the class of sets that are polynomial time reducible to a sparse set. It is widely believed, but unfortunately up to now unproven, that there are sets in $EXP^{NP}$, or even ... more >>>

TR10-164 | 4th November 2010
Falk Unger

Better gates can make fault-tolerant computation impossible

Revisions: 1

We consider fault-tolerant computation with formulas composed of noisy Boolean gates with two input wires. In our model all gates fail independently of each other and of the input. When a gate fails, it outputs the opposite of the correct output. It is known that if all gates fail with ... more >>>

TR10-165 | 4th November 2010
Dmitry Gavinsky, Tsuyoshi Ito

Quantum Fingerprints that Keep Secrets

We introduce a new type of cryptographic primitive that we call hiding fingerprinting. No classical fingerprinting scheme is hiding. We construct quantum hiding fingerprinting schemes and argue their optimality.

more >>>

TR10-166 | 5th November 2010
Mark Braverman, Anup Rao

Towards Coding for Maximum Errors in Interactive Communication

We show that it is possible to encode any communication protocol
between two parties so that the protocol succeeds even if a $(1/4 -
\epsilon)$ fraction of all symbols transmitted by the parties are
corrupted adversarially, at a cost of increasing the communication in
the protocol by a constant factor ... more >>>

TR10-167 | 5th November 2010
Nitin Saxena, C. Seshadhri

Blackbox identity testing for bounded top fanin depth-3 circuits: the field doesn't matter

Let C be a depth-3 circuit with n variables, degree d and top fanin k (called sps(k,d,n) circuits) over base field F.
It is a major open problem to design a deterministic polynomial time blackbox algorithm
that tests if C is identically zero.
Klivans & Spielman (STOC 2001) observed ... more >>>

TR10-168 | 9th November 2010
Thomas Watson

Pseudorandom Generators for Combinatorial Checkerboards

Revisions: 2

We define a combinatorial checkerboard to be a function $f:\{1,\ldots,m\}^d\to\{1,-1\}$ of the form $f(u_1,\ldots,u_d)=\prod_{i=1}^df_i(u_i)$ for some functions $f_i:\{1,\ldots,m\}\to\{1,-1\}$. This is a variant of combinatorial rectangles, which can be defined in the same way but using $\{0,1\}$ instead of $\{1,-1\}$. We consider the problem of constructing explicit pseudorandom generators for combinatorial ... more >>>

TR10-169 | 10th November 2010
Siavosh Benabbas, Konstantinos Georgiou, Avner Magen

The Sherali-Adams System Applied to Vertex Cover: Why Borsuk Graphs Fool Strong LPs and some Tight Integrality Gaps for SDPs

Revisions: 2

We study the performance of the Sherali-Adams system for VERTEX COVER on graphs with vector
chromatic number $2+\epsilon$. We are able to construct solutions for LPs derived by any number of Sherali-Adams tightenings by introducing a new tool to establish Local-Global Discrepancy. When restricted to
$O(1/ \epsilon)$ tightenings we show ... more >>>

TR10-170 | 11th November 2010
Scott Aaronson, Alex Arkhipov

The Computational Complexity of Linear Optics

We give new evidence that quantum computers -- moreover, rudimentary quantum computers built entirely out of linear-optical elements -- cannot be efficiently simulated by classical computers. In particular, we define a
model of computation in which identical photons are generated, sent through a linear-optical network, then nonadaptively measured to count ... more >>>

TR10-171 | 11th November 2010
Michael Viderman

A Note on high-rate Locally Testable Codes with sublinear query complexity

Inspired by recent construction of high-rate locally correctable codes with sublinear query complexity due to
Kopparty, Saraf and Yekhanin (2010) we address the similar question for locally testable codes (LTCs).

In this note we show a construction of high-rate LTCs with sublinear query complexity.
More formally, we show that for ... more >>>

TR10-172 | 11th November 2010
Prasad Raghavendra, David Steurer, Madhur Tulsiani

Reductions Between Expansion Problems

The Small-Set Expansion Hypothesis (Raghavendra, Steurer, STOC 2010) is a natural hardness assumption concerning the problem of approximating the edge expansion of small sets in graphs. This hardness assumption is closely connected to the Unique Games Conjecture (Khot, STOC 2002). In particular, the Small-Set Expansion Hypothesis implies the Unique ... more >>>

TR10-173 | 9th November 2010
Yeow Meng Chee, Tao Feng, San Ling, Huaxiong Wang, Liang Feng Zhang

Query-Efficient Locally Decodable Codes

A $k$-query locally decodable code (LDC)
$\textbf{C}:\Sigma^{n}\rightarrow \Gamma^{N}$ encodes each message $x$ into
a codeword $\textbf{C}(x)$ such that each symbol of $x$ can be probabilistically
recovered by querying only $k$ coordinates of $\textbf{C}(x)$, even after a
constant fraction of the coordinates have been corrupted.
Yekhanin (2008)
constructed a $3$-query LDC ... more >>>

TR10-174 | 12th November 2010
Scott Aaronson, Baris Aydinlioglu, Harry Buhrman, John Hitchcock, Dieter van Melkebeek

A note on exponential circuit lower bounds from derandomizing Arthur-Merlin games

We present an alternate proof of the recent result by Gutfreund and Kawachi that derandomizing Arthur-Merlin games into $P^{NP}$ implies linear-exponential circuit lower bounds for $E^{NP}$. Our proof is simpler and yields stronger results. In particular, consider the promise-$AM$ problem of distinguishing between the case where a given Boolean circuit ... more >>>

TR10-175 | 14th November 2010
Emanuele Viola

Randomness buys depth for approximate counting

Revisions: 1

We show that the promise problem of distinguishing $n$-bit strings of hamming weight $\ge 1/2 + \Omega(1/\log^{d-1} n)$ from strings of weight $\le 1/2 - \Omega(1/\log^{d-1} n)$ can be solved by explicit, randomized (unbounded-fan-in) poly(n)-size depth-$d$ circuits with error $\le 1/3$, but cannot be solved by deterministic poly(n)-size depth-$(d+1)$ circuits, ... more >>>

TR10-176 | 15th November 2010
Parikshit Gopalan, Raghu Meka, Omer Reingold, David Zuckerman

Pseudorandom Generators for Combinatorial Shapes

Revisions: 1

We construct pseudorandom generators for combinatorial shapes, which substantially generalize combinatorial rectangles, small-bias spaces, 0/1 halfspaces, and 0/1 modular sums. A function $f:[m]^n \rightarrow \{0,1\}^n$ is an $(m,n)$-combinatorial shape if there exist sets $A_1,\ldots,A_n \subseteq [m]$ and a symmetric function $h:\{0,1\}^n \rightarrow \{0,1\}$ such that $f(x_1,\ldots,x_n) = h(1_{A_1} (x_1),\ldots,1_{A_n}(x_n))$. Our ... more >>>

TR10-177 | 16th November 2010
Venkatesan Guruswami, Prasad Raghavendra, Rishi Saket, Yi Wu

Bypassing UGC from some optimal geometric inapproximability results

Revisions: 1

The Unique Games conjecture (UGC) has emerged in recent years as the starting point for several optimal inapproximability results. While for none of these results a reverse reduction to Unique Games is known, the assumption of bijective projections in the Label Cover instance seems critical in these proofs. In this ... more >>>

TR10-178 | 17th November 2010
Amir Shpilka, Avishay Tal

On the Minimal Fourier Degree of Symmetric Boolean Functions

In this paper we give a new upper bound on the minimal degree of a nonzero Fourier coefficient in any non-linear symmetric Boolean function.
Specifically, we prove that for every non-linear and symmetric $f:\{0,1\}^{k} \to \{0,1\}$ there exists a set $\emptyset\neq S\subset[k]$ such that $|S|=O(\Gamma(k)+\sqrt{k})$, and $\hat{f}(S) \neq 0$, where ... more >>>

TR10-179 | 18th November 2010
Gregory Valiant, Paul Valiant

A CLT and tight lower bounds for estimating entropy

Revisions: 1

We prove two new multivariate central limit theorems; the first relates the sum of independent distributions to the multivariate Gaussian of corresponding mean and covariance, under the earthmover distance matric (also known as the Wasserstein metric). We leverage this central limit theorem to prove a stronger but more specific central ... more >>>

TR10-180 | 18th November 2010
Gregory Valiant, Paul Valiant

Estimating the unseen: A sublinear-sample canonical estimator of distributions

We introduce a new approach to characterizing the unobserved portion of a distribution, which provides sublinear-sample additive estimators for a class of properties that includes entropy and distribution support size. Together with the lower bounds proven in the companion paper [29], this settles the longstanding question of the sample complexities ... more >>>

TR10-181 | 21st November 2010
Hamed Hatami, Shachar Lovett

Higher-order Fourier analysis of $\mathbb{F}_p^n$ and the complexity of systems of linear forms

In this article we are interested in the density of small linear structures (e.g. arithmetic progressions) in subsets $A$ of the group $\mathbb{F}_p^n$. It is possible to express these densities as certain analytic averages involving $1_A$, the indicator function of $A$. In the higher-order Fourier analytic approach, the function $1_A$ ... more >>>

TR10-182 | 26th November 2010
Shachar Lovett

An elementary proof of anti-concentration of polynomials in Gaussian variables

Recently there has been much interest in polynomial threshold functions in the context of learning theory, structural results and pseudorandomness. A crucial ingredient in these works is the understanding of the distribution of low-degree multivariate polynomials evaluated over normally distributed inputs. In particular, the two important properties are exponential tail ... more >>>

TR10-183 | 29th November 2010
Raghu Meka

Almost Optimal Explicit Johnson-Lindenstrauss Transformations

Revisions: 2

The Johnson-Lindenstrauss lemma is a fundamental result in probability with several applications in the design and analysis of algorithms in high dimensional geometry. Most known constructions of linear embeddings that satisfy the Johnson-Lindenstrauss property involve randomness. We address the question of explicitly constructing such embedding families and provide a construction ... more >>>

TR10-184 | 19th November 2010
Manjish Pal

Combinatorial Geometry of Graph Partitioning - I

The {\sc $c$-Balanced Separator} problem is a graph-partitioning problem in which given a graph $G$, one aims to find a cut of minimum size such that both the sides of the cut have at least $cn$ vertices. In this paper, we present new directions of progress in the {\sc $c$-Balanced ... more >>>

TR10-185 | 2nd December 2010
Vitaly Feldman, Venkatesan Guruswami, Prasad Raghavendra, Yi Wu

Agnostic Learning of Monomials by Halfspaces is Hard

We prove the following strong hardness result for learning: Given a distribution of labeled examples from the hypercube such that there exists a monomial consistent with $(1-\epsilon)$ of the examples, it is $\mathrm{NP}$-hard to find a halfspace that is correct on $(1/2+\epsilon)$ of the examples, for arbitrary constants $\epsilon ... more >>>

TR10-186 | 2nd December 2010
Bill Fefferman, Ronen Shaltiel, Chris Umans, Emanuele Viola

On beating the hybrid argument

The {\em hybrid argument}
allows one to relate
the {\em distinguishability} of a distribution (from
uniform) to the {\em
predictability} of individual bits given a prefix. The
argument incurs a loss of a factor $k$ equal to the
bit-length of the
distributions: $\epsilon$-distinguishability implies only
$\epsilon/k$-predictability. ... more >>>

TR10-187 | 3rd December 2010
Gus Gutoski

Interactive proofs with competing teams of no-signaling provers

Revisions: 2

This paper studies a generalization of multi-prover interactive proofs in which a verifier interacts with two competing teams of provers: one team attempts to convince the verifier to accept while the other attempts to convince the verifier to reject. Each team consists of two provers who jointly implement a no-signaling ... more >>>

TR10-188 | 8th December 2010
Matthew Anderson, Dieter van Melkebeek, Ilya Volkovich

Derandomizing Polynomial Identity Testing for Multilinear Constant-Read Formulae

Revisions: 1

We present a polynomial-time deterministic algorithm for testing whether constant-read multilinear arithmetic formulae are identically zero. In such a formula each variable occurs only a constant number of times and each subformula computes a multilinear polynomial. Our algorithm runs in time $s^{O(1)}\cdot n^{k^{O(k)}}$, where $s$ denotes the size of the ... more >>>

TR10-189 | 8th December 2010
Neeraj Kayal, Chandan Saha

On the Sum of Square Roots of Polynomials and related problems

The sum of square roots problem over integers is the task of deciding the sign of a nonzero sum, $S = \Sigma_{i=1}^{n}{\delta_i}$ . \sqrt{$a_i$}, where $\delta_i \in$ { +1, -1} and $a_i$'s are positive integers that are upper bounded by $N$ (say). A fundamental open question in numerical analysis and ... more >>>

TR10-190 | 9th December 2010
Xin Li

Improved Constructions of Three Source Extractors

We study the problem of constructing extractors for independent weak random sources. The probabilistic method shows that there exists an extractor for two independent weak random sources on $n$ bits with only logarithmic min-entropy. However, previously the best known explicit two source extractor only achieves min-entropy $0.499n$ \cite{Bourgain05}, and the ... 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 >>>

TR10-192 | 8th December 2010
Frederic Magniez, Ashwin Nayak, Miklos Santha, David Xiao

Improved bounds for the randomized decision tree complexity of recursive majority

Revisions: 1

We consider the randomized decision tree complexity of the recursive 3-majority function. For evaluating a height $h$ formulae, we prove a lower bound for the $\delta$-two-sided-error randomized decision tree complexity of $(1-2\delta)(5/2)^h$, improving the lower bound of $(1-2\delta)(7/3)^h$ given by Jayram et al. (STOC '03). We also state a conjecture ... more >>>

TR10-193 | 5th December 2010
Edward Hirsch, Dmitry Itsykson, Ivan Monakhov, Alexander Smal

On optimal heuristic randomized semidecision procedures, with applications to proof complexity and cryptography

The existence of an optimal propositional proof system is a major open question in proof complexity; many people conjecture that such systems do not exist. Krajicek and Pudlak (1989) show that this question is equivalent to the existence of an algorithm that is optimal on all propositional tautologies. Monroe (2009) ... more >>>

TR10-194 | 9th December 2010
Thanh Minh Hoang

Isolation of Matchings via Chinese Remaindering

In this paper we investigate the question whether a perfect matching can be isolated by a weighting scheme
using Chinese Remainder Theorem (short: CRT). We give a systematical analysis to a method based on CRT
suggested by Agrawal in a CCC'03-paper
for testing perfect matchings. We show that ... more >>>

TR10-195 | 13th November 2010
Ho-Lin Chen, David Doty, Shinnosuke Seki, David Soloveichik

Parallelism, Program Size, Time, and Temperature in Self-Assembly

Revisions: 1

We settle a number of questions in variants of Winfree's abstract Tile Assembly Model (aTAM), a model of molecular algorithmic self-assembly. In the "hierarchical" aTAM, two assemblies, both consisting of multiple tiles, are allowed to aggregate together, whereas in the "seeded" aTAM, tiles attach one at a time to a ... more >>>

TR10-196 | 8th December 2010
Bin Fu

NE is not NP Turing Reducible to Nonexpoentially Dense NP Sets

A long standing open problem in the computational complexity theory
is to separate NE from BPP, which is a subclass of $NP_T (NP\cap P/poly)$.
In this paper, we show that $NE\not\subseteq NP_T (NP \cap$ Nonexponentially-Dense-Class),
where Nonexponentially-Dense-Class is the class of languages A without exponential density
(for ... more >>>

TR10-197 | 14th December 2010
Albert Atserias, Elitza Maneva

Mean-payoff games and propositional proofs

We associate a CNF-formula to every instance of the mean-payoff game problem in such a way that if the value of the game is non-negative the formula is satisfiable, and if the value of the game is negative the formula has a polynomial-size refutation in $\Sigma_2$-Frege (i.e.~DNF-resolution). This reduces mean-payoff ... 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 >>>

TR10-199 | 14th December 2010
Eli Ben-Sasson, Ghid Maatouk, Amir Shpilka, Madhu Sudan

Symmetric LDPC codes are not necessarily locally testable

Locally testable codes, i.e., codes where membership in the code is testable with a constant number of queries, have played a central role in complexity theory. It is well known that a code must be a "low-density parity check" (LDPC) code for it to be locally testable, but few LDPC ... more >>>

TR10-200 | 14th December 2010
Eli Ben-Sasson, Michael Viderman

Towards lower bounds on locally testable codes via density arguments

The main open problem in the area of locally testable codes (LTCs) is whether there exists an asymptotically good family of LTCs and to resolve this question it suffices to consider the case of query complexity $3$. We argue that to refute the existence of such an asymptotically good family ... more >>>

TR10-201 | 21st December 2010
Samir Datta, Raghav Kulkarni, Raghunath Tewari

Perfect Matching in Bipartite Planar Graphs is in UL

Revisions: 1

We prove that Perfect Matching in bipartite planar graphs is in UL, improving upon
the previous bound of SPL (see [DKR10]) on its space complexity. We also exhibit space
complexity bounds for some related problems. Summarizing, we show that, constructing:
1. a Perfect Matching in bipartite planar graphs is in ... more >>>

TR10-202 | 9th December 2010
Bin Fu

Multivariate Polynomial Integration and Derivative Are Polynomial Time Inapproximable unless P=NP

We investigate the complexity of integration and
derivative for multivariate polynomials in the standard computation
model. The integration is in the unit cube $[0,1]^d$ for a
multivariate polynomial, which has format
x_d)=p_1(x_1,\cdots, x_d)p_2(x_1,\cdots, x_d)\cdots p_k(x_1,\cdots,
where each $p_i(x_1,\cdots, x_d)=\sum_{j=1}^d q_j(x_j)$ with
all single variable polynomials $q_j(x_j)$ ... more >>>

ISSN 1433-8092 | Imprint