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Electronic Colloquium on Computational Complexity

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REPORTS > 2011:
All reports in year 2011:
TR11-001 | 2nd January 2011
Scott Aaronson

Impossibility of Succinct Quantum Proofs for Collision-Freeness

We show that any quantum algorithm to decide whether a function $f:\left[n\right] \rightarrow\left[ n\right] $ is a permutation or far from a permutation\ must make $\Omega\left( n^{1/3}/w\right) $ queries to $f$, even if the algorithm is given a $w$-qubit quantum witness in support of $f$ being a permutation. This implies ... more >>>


TR11-002 | 9th January 2011
Gil Cohen, Amir Shpilka, Avishay Tal

On the Degree of Univariate Polynomials Over the Integers

We study the following problem raised by von zur Gathen and Roche:

What is the minimal degree of a nonconstant polynomial $f:\{0,\ldots,n\}\to\{0,\ldots,m\}$?

Clearly, when $m=n$ the function $f(x)=x$ has degree $1$. We prove that when $m=n-1$ (i.e. the point $\{n\}$ is not in the range), it must be the case ... more >>>


TR11-003 | 10th January 2011
Yehuda Lindell

Constant-Round Zero-Knowledge Proofs of Knowledge

Revisions: 1

In this note, we show the existence of \emph{constant-round} computational zero-knowledge \emph{proofs of knowledge} for all $\cal NP$. The existence of constant-round zero-knowledge proofs was proven by Goldreich and Kahan (Journal of Cryptology, 1996), and the existence of constant-round zero-knowledge \emph{arguments} of knowledge was proven by Feige and Shamir (CRYPTO ... more >>>


TR11-004 | 10th January 2011
Oded Goldreich, Salil Vadhan

On the complexity of computational problems regarding distributions (a survey)

We consider two basic computational problems
regarding discrete probability distributions:
(1) approximating the statistical difference (aka variation distance)
between two given distributions,
and (2) approximating the entropy of a given distribution.
Both problems are considered in two different settings.
In the first setting the approximation algorithm
more >>>


TR11-005 | 20th January 2011
Madhu Sudan

Testing Linear Properties: Some general themes

Revisions: 1

The last two decades have seen enormous progress in the development of sublinear-time algorithms --- i.e., algorithms that examine/reveal properties of ``data'' in less time than it would take to read all of the data. A large, and important, subclass of such properties turn out to be ``linear''. In particular, ... more >>>


TR11-006 | 20th January 2011
Sebastian Müller, Iddo Tzameret

Average-Case Separation in Proof Complexity: Short Propositional Refutations for Random 3CNF Formulas

Revisions: 1

Separating different propositional proof systems---that is, demonstrating that one proof system cannot efficiently simulate another proof system---is one of the main goals of proof complexity. Nevertheless, all known separation results between non-abstract proof systems are for specific families of hard tautologies: for what we know, in the average case all ... more >>>


TR11-007 | 17th January 2011
Benny Applebaum

Pseudorandom Generators with Long Stretch and Low locality from Random Local One-Way Functions

Revisions: 3

We continue the study of pseudorandom generators (PRG) $G:\{0,1\}^n \rightarrow \{0,1\}^m$ in NC0. While it is known that such generators are likely to exist for the case of small sub-linear stretch $m=n+n^{1-\epsilon}$, it remains unclear whether achieving larger stretch such as $m=2n$ or even $m=n+n^2$ is possible. The existence of ... more >>>


TR11-008 | 27th January 2011
Scott Aaronson, Andrew Drucker

Advice Coins for Classical and Quantum Computation

We study the power of classical and quantum algorithms equipped with nonuniform advice, in the form of a coin whose bias encodes useful information. This question takes on particular importance in the quantum case, due to a surprising result that we prove: a quantum finite automaton with just two states ... more >>>


TR11-009 | 21st January 2011
Samir Datta, Gautam Prakriya

Planarity Testing Revisited

Planarity Testing is the problem of determining whether a given graph is planar while planar embedding is the corresponding construction problem.
The bounded space complexity of these problems has been determined to be Logspace by Allender and Mahajan with the aid of Reingold's result . Unfortunately, the algorithm is quite ... more >>>


TR11-010 | 1st February 2011
Boris Alexeev, Michael Forbes, Jacob Tsimerman

Tensor Rank: Some Lower and Upper Bounds

The results of Strassen and Raz show that good enough tensor rank lower bounds have implications for algebraic circuit/formula lower bounds.

We explore tensor rank lower and upper bounds, focusing on explicit tensors. For odd d, we construct field-independent explicit 0/1 tensors T:[n]^d->F with rank at least 2n^(floor(d/2))+n-Theta(d log n). ... more >>>


TR11-011 | 1st February 2011
Ming Lam Leung, Yang Li, Shengyu Zhang

Tight bounds on the randomized communication complexity of symmetric XOR functions in one-way and SMP models

We study the communication complexity of symmetric XOR functions, namely functions $f: \{0,1\}^n \times \{0,1\}^n \rightarrow \{0,1\}$ that can be formulated as $f(x,y)=D(|x\oplus y|)$ for some predicate $D: \{0,1,...,n\} \rightarrow \{0,1\}$, where $|x\oplus y|$ is the Hamming weight of the bitwise XOR of $x$ and $y$. We give a public-coin ... more >>>


TR11-012 | 2nd February 2011
Andrej Bogdanov, Alon Rosen

Input locality and hardness amplification

We establish new hardness amplification results for one-way functions in which each input bit influences only a small number of output bits (a.k.a. input-local functions). Our transformations differ from previous ones in that they approximately preserve input locality and at the same time retain the input size of the original ... more >>>


TR11-013 | 3rd February 2011
Ronitt Rubinfeld, Asaf Shapira

Sublinear Time Algorithms

Sublinear time algorithms represent a new paradigm
in computing, where an algorithm must give some sort
of an answer after inspecting only a very small portion
of the input. We discuss the types of answers that
one can hope to achieve in this setting.

more >>>

TR11-014 | 3rd February 2011
Antoine Taveneaux

Towards an axiomatic system for Kolmogorov complexity

Revisions: 1

In \cite{shenpapier82}, it is shown that four basic functional properties are enough to characterize plain Kolmogorov complexity, hence obtaining an axiomatic characterization of this notion. In this paper, we try to extend this work, both by looking at alternative axiomatic systems for plain complexity and by considering potential axiomatic systems ... more >>>


TR11-015 | 8th December 2010
Marcel R. Ackermann, Johannes Blömer, Christoph Scholz

Hardness and Non-Approximability of Bregman Clustering Problems

We prove the computational hardness of three k-clustering problems using an (almost) arbitrary Bregman divergence as dissimilarity measure: (a) The Bregman k-center problem, where the objective is to find a set of centers that minimizes the maximum dissimilarity of any input point towards its closest center, and (b) the Bregman ... more >>>


TR11-016 | 7th February 2011
Sergei Artemenko, Ronen Shaltiel

Lower bounds on the query complexity of non-uniform and adaptive reductions showing hardness amplification

Revisions: 1

Hardness amplification results show that for every function $f$ there exists a function $Amp(f)$ such that the following holds: if every circuit of size $s$ computes $f$ correctly on at most a $1-\delta$ fraction of inputs, then every circuit of size $s'$ computes $Amp(f)$ correctly on at most a $1/2+\eps$ ... more >>>


TR11-017 | 8th February 2011
Fengming Wang

NEXP does not have non-uniform quasi-polynomial-size ACC circuits of o(loglog n) depth

$\mbox{ACC}_m$ circuits are circuits consisting of unbounded fan-in AND, OR and MOD_m gates and unary NOT gates, where m is a fixed integer. We show that there exists a language in non-deterministic exponential time which can not be computed by any non-uniform family of $\mbox{ACC}_m$ circuits of quasi-polynomial size and ... more >>>


TR11-018 | 8th February 2011
Jochen Messner, Thomas Thierauf

A Kolmogorov Complexity Proof of the Lovász Local Lemma for Satisfiability

Recently, Moser and Tardos [MT10] came up with a constructive proof of the Lovász Local Lemma. In this paper, we give another constructive proof of the lemma, based on Kolmogorov complexity. Actually, we even improve the Local Lemma slightly.

more >>>

TR11-019 | 5th February 2011
Valentin Brimkov, Andrew Leach, Jimmy Wu, Michael Mastroianni

On the Approximability of a Geometric Set Cover Problem

Given a finite set of straight line segments $S$ in $R^{2}$ and some $k\in N$, is there a subset $V$ of points on segments in $S$ with $\vert V \vert \leq k$ such that each segment of $S$ contains at least one point in $V$? This is a special case ... more >>>


TR11-020 | 20th December 2010
Yijia Chen, Joerg Flum

Listings and logics

There are standard logics DTC, TC, and LFP capturing the complexity classes L, NL, and P on ordered structures, respectively. In [Chen and Flum, 2010] we have shown that ${\rm LFP}_{\rm inv}$, the ``order-invariant least fixed-point logic LFP,'' captures P (on all finite structures) if and only if there is ... more >>>


TR11-021 | 13th February 2011
Chandan Saha, Ramprasad Saptharishi, Nitin Saxena

A Case of Depth-3 Identity Testing, Sparse Factorization and Duality

Finding an efficient solution to the general problem of polynomial identity testing (PIT) is a challenging task. In this work, we study the complexity of two special but natural cases of identity testing - first is a case of depth-$3$ PIT, the other of depth-$4$ PIT.

Our first problem is ... more >>>


TR11-022 | 14th February 2011
Malte Beecken, Johannes Mittmann, Nitin Saxena

Algebraic Independence and Blackbox Identity Testing

Algebraic independence is an advanced notion in commutative algebra that generalizes independence of linear polynomials to higher degree. Polynomials $\{f_1,\ldots, f_m\} \subset \mathbb{F}[x_1,\ldots, x_n]$ are called algebraically independent if there is no non-zero polynomial $F$ such that $F(f_1, \ldots, f_m) = 0$. The transcendence degree, $\mbox{trdeg}\{f_1,\ldots, f_m\}$, is the maximal ... more >>>


TR11-023 | 16th February 2011
Oded Goldreich, Or Meir

Input-Oblivious Proof Systems and a Uniform Complexity Perspective on P/poly

Revisions: 5 , Comments: 2

We initiate a study of input-oblivious proof systems, and present a few preliminary results regarding such systems.
Our results offer a perspective on the intersection of the non-uniform complexity class P/poly with uniform complexity classes such as NP and IP.
In particular, we provide a uniform complexity formulation of the ... more >>>


TR11-024 | 25th February 2011
Rahul Jain

New strong direct product results in communication complexity

We show two new direct product results in two different models of communication complexity. Our first result is in the model of one-way public-coin model. Let $f \subseteq X \times Y \times Z $ be a relation and $\epsilon >0$ be a constant. Let $R^{1,pub}_{\epsilon}(f)$ represent the communication complexity of ... more >>>


TR11-025 | 19th February 2011
Yang Li

Monotone Rank and Separations in Computational Complexity

Revisions: 1 , Comments: 1

In the paper, we introduce the concept of monotone rank, and using it as a powerful tool, we obtain several important and strong separation results in computational complexity.

\begin{itemize}

\item We show a super-exponential separation between monotone and non-monotone computation in the non-commutative model, and thus give the answer to ... more >>>


TR11-026 | 27th February 2011
Evgeny Demenkov, Alexander Kulikov

An Elementary Proof of $3n-o(n)$ Lower Bound on the Circuit Complexity of Affine Dispersers

A Boolean function $f \colon \mathbb{F}^n_2 \rightarrow \mathbb{F}_2$ is called an affine disperser for sources of dimension $d$, if $f$ is not constant on any affine subspace of $\mathbb{F}^n_2$ of dimension at least $d$. Recently Ben-Sasson and Kopparty gave an explicit construction of an affine disperser for $d=o(n)$. The main ... more >>>


TR11-027 | 28th February 2011
Venkatesan Guruswami, Johan Hastad, Rajsekar Manokaran, Prasad Raghavendra, Moses Charikar

Beating the Random Ordering is Hard: Every ordering CSP is approximation resistant

We prove that, assuming the Unique Games Conjecture (UGC), every problem in the class of ordering constraint satisfaction problems (OCSP) where each constraint has constant arity is approximation
resistant. In other words, we show that if $\rho$ is the expected fraction of constraints satisfied by a random ordering, then obtaining ... more >>>


TR11-028 | 24th February 2011
Richard Beigel, Bin Fu

A Dense Hierarchy of Sublinear Time Approximation Schemes for Bin Packing

The bin packing problem is to find the minimum
number of bins of size one to pack a list of items with sizes
$a_1,\ldots , a_n$ in $(0,1]$. Using uniform sampling, which selects
a random element from the input list each time, we develop a
randomized $O({n(\log n)(\log\log n)\over ... more >>>


TR11-029 | 6th March 2011
Hamed Hatami, Shachar Lovett

Correlation testing for affine invariant properties on $\mathbb{F}_p^n$ in the high error regime

Revisions: 1

Recently there has been much interest in Gowers uniformity norms from the perspective of theoretical computer science. This is mainly due to the fact that these norms provide a method for testing whether the maximum correlation of a function $f:\mathbb{F}_p^n \rightarrow \mathbb{F}_p$ with polynomials of degree at most $d \le ... more >>>


TR11-030 | 9th March 2011
Anna Gal, Andrew Mills

Three Query Locally Decodable Codes with Higher Correctness Require Exponential Length

Locally decodable codes
are error correcting codes with the extra property that, in order
to retrieve the correct value of just one position of the input with
high probability, it is
sufficient to read a small number of
positions of the corresponding,
possibly corrupted ... more >>>


TR11-031 | 8th March 2011
Sam Buss, Ryan Williams

Limits on Alternation-Trading Proofs for Time-Space Lower Bounds

This paper characterizes alternation trading based proofs that satisfiability is not in the time and space bounded class $\DTISP(n^c, n^\epsilon)$, for various values $c<2$ and $\epsilon<1$. We characterize exactly what can be proved in the $\epsilon=0$ case with currently known methods, and prove the conjecture of Williams that $c=2\cos(\pi/7)$ is ... more >>>


TR11-032 | 11th March 2011
Fabian Wagner

Graphs of Bounded Treewidth can be Canonized in AC$^1$

In recent results the complexity of isomorphism testing on
graphs of bounded treewidth is improved to TC$^1$ [GV06] and further to LogCFL [DTW10].
The computation of canonical forms or a canonical labeling provides more information than
isomorphism testing.
Whether canonization is in NC or even TC$^1$ was stated ... more >>>


TR11-033 | 8th March 2011
Rahul Jain, Shengyu Zhang

The influence lower bound via query elimination

We give a simpler proof, via query elimination, of a result due to O'Donnell, Saks, Schramm and Servedio, which shows a lower bound on the zero-error randomized query complexity of a function $f$ in terms of the maximum influence of any variable of $f$. Our lower bound also applies to ... more >>>


TR11-034 | 20th January 2011
Pavol Duris, Marek Kosta

Flip-Pushdown Automata with k Pushdown Reversals and E0L Systems are Incomparable

We prove that any propagating E0L system cannot generate the language containing all words of the form w#w. This result, together with some known ones, enable us to conclude that the flip-pushdown automata with k pushdown reversals (i.e. the pushdown automata with the ability to flip its pushdown) and E0L ... more >>>


TR11-035 | 4th March 2011
Christoph Behle, Andreas Krebs, Stephanie Reifferscheid

Typed Monoids -- An Eilenberg-like Theorem for non regular Languages

Based on different concepts to obtain a finer notion of language recognition via finite monoids we develop an algebraic structure called typed monoid.
This leads to an algebraic description of regular and non regular languages.

We obtain for each language a unique minimal recognizing typed monoid, the typed syntactic monoid.
more >>>


TR11-036 | 17th March 2011
Gilad Asharov, Yehuda Lindell

A Full Proof of the BGW Protocol for Perfectly-Secure Multiparty Computation

Revisions: 4

In the setting of secure multiparty computation, a set of $n$ parties with private inputs wish to jointly compute some functionality of their inputs. One of the most fundamental results of information-theoretically secure computation was presented by Ben-Or, Goldwasser and Wigderson (BGW) in 1988. They demonstrated that any $n$-party functionality ... more >>>


TR11-037 | 18th March 2011
Anindya De, Thomas Watson

Extractors and Lower Bounds for Locally Samplable Sources

Revisions: 3

We consider the problem of extracting randomness from sources that are efficiently samplable, in the sense that each output bit of the sampler only depends on some small number $d$ of the random input bits. As our main result, we construct a deterministic extractor that, given any $d$-local source with ... more >>>


TR11-038 | 10th March 2011
Jiapeng Zhang

On the query complexity for Showing Dense Model

A theorem of Green, Tao, and Ziegler can be stated as follows: if $R$ is a pseudorandom distribution, and $D$ is a dense distribution of $R,$ then $D$ can be modeled as a distribution $M$ which is dense in uniform distribution such that $D$ and $M$ are indistinguishable. The reduction ... more >>>


TR11-039 | 19th March 2011
Frederic Green, Daniel Kreymer, Emanuele Viola

In Brute-Force Search of Correlation Bounds for Polynomials

We report on some initial results of a brute-force search for determining the maximum correlation between degree-$d$ polynomials modulo $p$ and the $n$-bit mod $q$ function. For various settings of the parameters $n,d,p,$ and $q$, our results indicate that symmetric polynomials yield the maximum correlation. This contrasts with the previously-analyzed ... more >>>


TR11-040 | 22nd March 2011
Alexander A. Sherstov

Strong Direct Product Theorems for Quantum Communication and Query Complexity

A strong direct product theorem (SDPT) states that solving $n$ instances of a problem requires $\Omega(n)$ times the resources for a single instance, even to achieve success probability $2^{-\Omega(n)}.$ We prove that quantum communication complexity obeys an SDPT whenever the communication lower bound for a single instance is proved by ... more >>>


TR11-041 | 24th March 2011
Dana Ron, Gilad Tsur

Testing Computability by Width-Two OBDDs

Property testing is concerned with deciding whether an object
(e.g. a graph or a function) has a certain property or is ``far''
(for a prespecified distance measure) from every object with
that property. In this work we consider the property of being
computable by a read-once ... more >>>


TR11-042 | 25th March 2011
Ankur Moitra

Efficiently Coding for Interactive Communication

Revisions: 1

In 1992, Schulman proved a coding theorem for interactive communication and demonstrated that interactive communication protocols can be made robust to noise with only a constant slow-down (for a sufficiently small error rate) through a black-box reduction. However, this scheme is not computationally {\em efficient}: the running time to construct ... more >>>


TR11-043 | 25th March 2011
Scott Aaronson

A Linear-Optical Proof that the Permanent is #P-Hard

One of the crown jewels of complexity theory is Valiant's 1979 theorem that computing the permanent of an n*n matrix is #P-hard. Here we show that, by using the model of linear-optical quantum computing---and in particular, a universality theorem due to Knill, Laflamme, and Milburn---one can give a different and ... more >>>


TR11-044 | 25th March 2011
Shubhangi Saraf, Sergey Yekhanin

Noisy Interpolation of Sparse Polynomials, and Applications

Let $f\in F_q[x]$ be a polynomial of degree $d\leq q/2.$ It is well-known that $f$ can be uniquely recovered from its values at some $2d$ points even after some small fraction of the values are corrupted. In this paper we establish a similar result for sparse polynomials. We show that ... more >>>


TR11-045 | 1st April 2011
Eric Blais, Joshua Brody, Kevin Matulef

Property Testing Lower Bounds via Communication Complexity

Revisions: 1

We develop a new technique for proving lower bounds in property testing, by showing a strong connection between testing and communication complexity. We give a simple scheme for reducing communication problems to testing problems, thus allowing us to use known lower bounds in communication complexity to prove lower bounds in ... more >>>


TR11-046 | 2nd April 2011
Shubhangi Saraf, Ilya Volkovich

Black-Box Identity Testing of Depth-4 Multilinear Circuits

We study the problem of identity testing for multilinear $\Spsp(k)$ circuits, i.e. multilinear depth-$4$ circuits with fan-in $k$ at the top $+$ gate. We give the first polynomial-time deterministic
identity testing algorithm for such circuits. Our results also hold in the black-box setting.

The running time of our algorithm is ... more >>>


TR11-047 | 8th April 2011
Oded Goldreich

Two Comments on Targeted Canonical Derandomizers

We revisit the notion of a {\em targeted canonical derandomizer},
introduced in our recent ECCC Report (TR10-135) as a uniform notion of
a pseudorandom generator that suffices for yielding BPP=P.
The original notion was derived (as a variant of the standard notion
of a canonical derandomizer) by providing both ... more >>>


TR11-048 | 10th April 2011
Arkadev Chattopadhyay, Shachar Lovett

Linear systems over abelian groups

We consider a system of linear constraints over any finite Abelian group $G$ of the following form: $\ell_i(x_1,\ldots,x_n) \equiv \ell_{i,1}x_1+\cdots+\ell_{i,n}x_n \in A_i$ for $i=1,\ldots,t$ and each $A_i \subset G$, $\ell_{i,j}$ is an element of $G$ and $x_i$'s are Boolean variables. Our main result shows that the subset of the Boolean ... more >>>


TR11-049 | 9th April 2011
Noga Alon, Shachar Lovett

Almost k-wise vs. k-wise independent permutations, and uniformity for general group actions

A family of permutations in $S_n$ is $k$-wise independent if a uniform permutation chosen from the family maps any distinct $k$ elements to any distinct $k$ elements equally likely. Efficient constructions of $k$-wise independent permutations are known for $k=2$ and $k=3$, but are unknown for $k \ge 4$. In fact, ... more >>>


TR11-050 | 11th April 2011
Claus-Peter Schnorr

Accelerated Slide- and LLL-Reduction

Revisions: 7

Given an LLL-basis $B$ of dimension $n= hk$ we accelerate slide-reduction with blocksize $k$ to run under a reasonable assjmption in \
$\frac1{6} \, n^2 h \,\log_{1+\varepsilon} \, \alpha $ \
local SVP-computations in dimension $k$, where $\alpha \ge \frac 43$
measures the quality of the ... more >>>


TR11-051 | 8th April 2011
Thomas Vidick

A concentration inequality for the overlap of a vector on a large set, With application to the communication complexity of the Gap-Hamming-Distance problem

Given two sets $A,B\subseteq\R^n$, a measure of their dependence, or correlation, is given by the expected squared inner product between random $x\in A $ and $y\in B$. We prove an inequality showing that no two sets of large enough Gaussian measure (at least $e^{-\delta n}$ for some constant $\delta >0$) ... more >>>


TR11-052 | 4th April 2011
Fabian Wagner

On the Complexity of Group Isomorphism

Revisions: 4 , Comments: 3

The group isomorphism problem consists in deciding whether two groups $G$ and $H$
given by their multiplication tables are isomorphic.
An algorithm for group isomorphism attributed to Tarjan runs in time $n^{\log n + O(1)}$, c.f. [Mil78].

Miller and Monk showed in [Mil79] that group isomorphism can be many-one ... more >>>


TR11-053 | 11th April 2011
Krzysztof Fleszar, Christian Glaßer, Fabian Lipp, Christian Reitwießner, Maximilian Witek

The Complexity of Solving Multiobjective Optimization Problems and its Relation to Multivalued Functions

Instances of optimization problems with multiple objectives can have several optimal solutions whose cost vectors are incomparable. This ambiguity leads to several reasonable notions for solving multiobjective problems. Each such notion defines a class of multivalued functions. We systematically investigate the computational complexity of these classes.

Some solution notions S ... more >>>


TR11-054 | 13th April 2011
Arnab Bhattacharyya, Zeev Dvir, Shubhangi Saraf, Amir Shpilka

Tight lower bounds for 2-query LCCs over finite fields

A Locally Correctable Code (LCC) is an error correcting code that has a probabilistic
self-correcting algorithm that, with high probability, can correct any coordinate of the
codeword by looking at only a few other coordinates, even if a fraction $\delta$ of the
coordinates are corrupted. LCC's are a stronger form ... more >>>


TR11-055 | 14th April 2011
Irit Dinur, Tali Kaufman

Dense locally testable codes cannot have constant rate and distance

A q-query locally testable code (LTC) is an error correcting code that can be tested by a randomized algorithm that reads at most q symbols from the given word.
An important question is whether there exist LTCs that have the ccc property: {c}onstant relative rate, {c}onstant relative distance, and that ... more >>>


TR11-056 | 14th April 2011
Emanuele Viola

Extractors for circuit sources

We obtain the first deterministic extractors for sources generated (or sampled) by small circuits of bounded depth. Our main results are:

(1) We extract $k (k/nd)^{O(1)}$ bits with exponentially small error from $n$-bit sources of min-entropy $k$ that are generated by functions $f : \{0,1\}^\ell \to \{0,1\}^n$ where each output ... more >>>


TR11-057 | 15th April 2011
Madhav Jha, Sofya Raskhodnikova

Testing and Reconstruction of Lipschitz Functions with Applications to Data Privacy

Revisions: 2

A function $f : D \to R$ has Lipschitz constant $c$ if $d_R(f(x),f(y)) \leq c\cdot d_D(x,y)$ for all $x,y$ in $D$, where $d_R$ and $d_D$ denote the distance functions on the range and domain of $f$, respectively. We say a function is Lipschitz if it has Lipschitz constant 1. (Note ... more >>>


TR11-058 | 15th April 2011
Michael Viderman

Linear time decoding of regular expander codes

Revisions: 1

Sipser and Spielman (IEEE IT, 1996) showed that any $(c,d)$-regular expander code with expansion parameter $> \frac{3}{4}$ is decodable in \emph{linear time} from a constant fraction of errors. Feldman et al. (IEEE IT, 2007)
proved that expansion parameter $> \frac{2}{3} + \frac{1}{3c}$ is sufficient to correct a constant fraction of ... more >>>


TR11-059 | 15th April 2011
Elad Haramaty, Amir Shpilka, Madhu Sudan

Optimal testing of multivariate polynomials over small prime fields

We consider the problem of testing if a given function $f : \F_q^n \rightarrow \F_q$ is close to a $n$-variate degree $d$ polynomial over the finite field $\F_q$ of $q$ elements. The natural, low-query, test for this property would be to pick the smallest dimension $t = t_{q,d}\approx d/q$ such ... more >>>


TR11-060 | 15th April 2011
Brady Garvin, Derrick Stolee, Raghunath Tewari, Vinodchandran Variyam

ReachFewL = ReachUL

We show that two complexity classes introduced about two decades ago are equal. ReachUL is the class of problems decided by nondeterministic log-space machines which on every input have at most one computation path from the start configuration to any other configuration. ReachFewL, a natural generalization of ReachUL, is the ... more >>>


TR11-061 | 18th April 2011
Neeraj Kayal

Affine projections of polynomials

Revisions: 1

An $m$-variate polynomial $f$ is said to be an affine projection of some $n$-variate polynomial $g$ if there exists an $n \times m$ matrix $A$ and an $n$-dimensional vector $b$ such that $f(x) = g(A x + b)$. In other words, if $f$ can be obtained by replacing each variable ... more >>>


TR11-062 | 18th April 2011
Amit Chakrabarti, Graham Cormode, Andrew McGregor

Robust Lower Bounds for Communication and Stream Computation

We study the communication complexity of evaluating functions when the input data is randomly allocated (according to some known distribution) amongst two or more players, possibly with information overlap. This naturally extends previously studied variable partition models such as the best-case and worst-case partition models. We aim to understand whether ... more >>>


TR11-063 | 19th April 2011
Alexander A. Sherstov

The Communication Complexity of Gap Hamming Distance


In the gap Hamming distance problem, two parties must
determine whether their respective strings $x,y\in\{0,1\}^n$
are at Hamming distance less than $n/2-\sqrt n$ or greater
than $n/2+\sqrt n.$ In a recent tour de force, Chakrabarti and
Regev (STOC '11) proved the long-conjectured $\Omega(n)$ bound
on the randomized communication ... more >>>


TR11-064 | 23rd April 2011
Mark Braverman

Towards deterministic tree code constructions

We present a deterministic operator on tree codes -- we call tree code product -- that allows one to deterministically combine two tree codes into a larger tree code. Moreover, if the original tree codes are efficiently encodable and decodable, then so is their product. This allows us to give ... more >>>


TR11-065 | 25th April 2011
Boaz Barak, Prasad Raghavendra, David Steurer

Rounding Semidefinite Programming Hierarchies via Global Correlation

We show a new way to round vector solutions of semidefinite programming (SDP) hierarchies into integral solutions, based on a connection between these hierarchies and the spectrum of the input graph. We demonstrate the utility of our method by providing a new SDP-hierarchy based algorithm for constraint satisfaction problems with ... more >>>


TR11-066 | 25th April 2011
Venkatesan Guruswami, Ali Kemal Sinop

Lasserre Hierarchy, Higher Eigenvalues, and Approximation Schemes for Quadratic Integer Programming with PSD Objectives

Revisions: 1

We present an approximation scheme for optimizing certain Quadratic Integer Programming problems with positive semidefinite objective functions and global linear constraints. This framework includes well known graph problems such as Minimum graph bisection, Edge expansion, Uniform sparsest cut, and Small Set expansion, as well as the Unique Games problem. These ... more >>>


TR11-067 | 25th April 2011
Noga Alon, Amir Shpilka, Chris Umans

On Sunflowers and Matrix Multiplication

Comments: 1

We present several variants of the sunflower conjecture of Erd\H{o}s and Rado and discuss the relations among them.

We then show that two of these conjectures (if true) imply negative answers to questions of Coppersmith and Winograd and Cohn et al. regarding possible approaches for obtaining fast matrix multiplication algorithms. ... more >>>


TR11-068 | 27th April 2011
L. Elisa Celis, Omer Reingold, Gil Segev, Udi Wieder

Balls and Bins: Smaller Hash Families and Faster Evaluation

A fundamental fact in the analysis of randomized algorithm is that when $n$ balls are hashed into $n$ bins independently and uniformly at random, with high probability each bin contains at most $O(\log n / \log \log n)$ balls. In various applications, however, the assumption that a truly random hash ... more >>>


TR11-069 | 18th April 2011
Marius Zimand

On the optimal compression of sets in PSPACE

We show that if DTIME[2^{O(n)}] is not included in DSPACE}[2^{o(n)}], then, for every set B in PSPACE, all strings x in B of length n can be represented by a string compressed(x) of length at most log (|B^{=n}|) + O(log n), such that a polynomial-time algorithm, given compressed(x), can distinguish ... more >>>


TR11-070 | 1st May 2011
Eli Ben-Sasson, Michael Viderman

Composition of semi-LTCs by two-wise Tensor Products

In this paper we obtain a composition theorem that allows us to construct locally testable codes (LTCs) by repeated two-wise tensor products. This is the First composition theorem showing that repeating the two-wise tensor operation any constant number of times still results in a locally testable code, improving upon previous ... more >>>


TR11-071 | 27th April 2011
Serge Gaspers, Stefan Szeider

The Parameterized Complexity of Local Consistency

Revisions: 1

We investigate the parameterized complexity of deciding whether a constraint network is $k$-consistent. We show that, parameterized by $k$, the problem is complete for the complexity class co-W[2]. As secondary parameters we consider the maximum domain size $d$ and the maximum number $\ell$ of constraints in which a variable occurs. ... more >>>


TR11-072 | 1st May 2011
Danny Hermelin, Xi Wu

Weak Compositions and Their Applications to Polynomial Lower-Bounds for Kernelization

Revisions: 1

We introduce a new form of composition called \emph{weak composition} that allows us to obtain polynomial kernelization lower-bounds for several natural parameterized problems. Let $d \ge 2$ be some constant and let $L_1, L_2 \subseteq \{0,1\}^* \times \N$ be two parameterized problems where the unparameterized version of $L_1$ is \NP-hard. ... more >>>


TR11-073 | 3rd May 2011
Andrew Drucker

Efficient Probabilistically Checkable Debates

Probabilistically checkable debate systems (PCDSs) are debates between two competing provers, in which a polynomial-time verifier inspects a constant number of bits of the debate. It was shown by Condon, Feigenbaum, Lund, and Shor that every language in PSPACE has a PCDS in which the debate length is polynomially bounded. ... more >>>


TR11-074 | 27th April 2011
Ludwig Staiger

Exact constructive dimension

Revisions: 1

The present paper generalises results by Lutz and Ryabko. We prove a
martingale characterisation of exact Hausdorff dimension. On this base we
introduce the notion of exact constructive dimension of (sets of) infinite
strings.

Furthermore, we generalise Ryabko's result on the Hausdorff dimension of the
... more >>>


TR11-075 | 6th May 2011
Arnab Bhattacharyya, Elena Grigorescu, Prasad Raghavendra, Asaf Shapira

Testing Odd-Cycle-Freeness in Boolean Functions

Call a function $f: \mathbb{F}_2^n \to \{0,1\}$ odd-cycle-free if there are no $x_1, \dots, x_k \in \mathbb{F}_2^n$ with $k$ an odd integer such that $f(x_1) = \cdots = f(x_k) = 1$ and $x_1 + \cdots + x_k = 0$. We show that one can distinguish odd-cycle-free functions from those $\epsilon$-far ... more >>>


TR11-076 | 7th May 2011
Eric Miles, Emanuele Viola

The Advanced Encryption Standard, Candidate Pseudorandom Functions, and Natural Proofs

Revisions: 1

We put forth several simple candidate pseudorandom functions f_k : {0,1}^n -> {0,1} with security (a.k.a. hardness) 2^n that are inspired by the AES block-cipher by Daemen and Rijmen (2000). The functions are computable more efficiently, and use a shorter key (a.k.a. seed) than previous
constructions. In particular, we ... more >>>


TR11-077 | 8th May 2011
Albert Atserias, Elitza Maneva

Graph Isomorphism, Sherali-Adams Relaxations and Expressibility in Counting Logics

Two graphs with adjacency matrices $\mathbf{A}$ and $\mathbf{B}$ are isomorphic if there exists a permutation matrix $\mathbf{P}$ for which the identity $\mathbf{P}^{\mathrm{T}} \mathbf{A} \mathbf{P} = \mathbf{B}$ holds. Multiplying through by $\mathbf{P}$ and relaxing the permutation matrix to a doubly stochastic matrix leads to the notion of fractional isomorphism. We show ... more >>>


TR11-078 | 9th May 2011
Dana Ron, Gilad Tsur

On Approximating the Number of Relevant Variables in a Function

In this work we consider the problem of approximating the number of relevant variables in a function given query access to the function. Since obtaining a multiplicative factor approximation is hard in general, we consider several relaxations of the problem. In particular, we consider relaxations in which we have a ... more >>>


TR11-079 | 9th May 2011
Eli Ben-Sasson, Elena Grigorescu, Ghid Maatouk, Amir Shpilka, Madhu Sudan

On Sums of Locally Testable Affine Invariant Properties

Affine-invariant properties are an abstract class of properties that generalize some
central algebraic ones, such as linearity and low-degree-ness, that have been
studied extensively in the context of property testing. Affine invariant properties
consider functions mapping a big field $\mathbb{F}_{q^n}$ to the subfield $\mathbb{F}_q$ and include all
properties that form ... more >>>


TR11-080 | 11th May 2011
mohammad iftekhar husain, steve ko, Atri Rudra, steve uurtamo

Storage Enforcement with Kolmogorov Complexity and List Decoding

We consider the following problem that arises in outsourced storage: a user stores her data $x$ on a remote server but wants to audit the server at some later point to make sure it actually did store $x$. The goal is to design a (randomized) verification protocol that has the ... more >>>


TR11-081 | 15th May 2011
Vikraman Arvind, Partha Mukhopadhyay, Prajakta Nimbhorkar

Erdos-Renyi Sequences and Deterministic construction of Expanding Cayley Graphs

Given a finite group $G$ by its multiplication table as input, we give a deterministic polynomial-time construction of a directed Cayley graph on $G$ with $O(\log |G|)$ generators, which has a rapid mixing property and a constant spectral expansion.\\

We prove a similar result in the undirected case, and ... more >>>


TR11-082 | 20th May 2011
Miklos Ajtai

Secure Computation with Information Leaking to an Adversary

Assume that Alice is running a program $P$ on a RAM, and an adversary
Bob would like to get some information about the input or output of the
program. At each time, during the execution of $P$, Bob is able to see
the addresses of the memory cells involved in ... more >>>


TR11-083 | 22nd May 2011
Eric Allender, Fengming Wang

On the power of algebraic branching programs of width two

We show that there are families of polynomials having small depth-two arithmetic circuits that cannot be expressed by algebraic branching programs of width two. This clarifies the complexity of the problem of computing the product of a sequence of two-by-two matrices, which arises in several
settings.

more >>>

TR11-084 | 23rd May 2011
Madhur Tulsiani, Julia Wolf

Quadratic Goldreich-Levin Theorems

Decomposition theorems in classical Fourier analysis enable us to express a bounded function in terms of few linear phases with large Fourier coefficients plus a part that is pseudorandom with respect to linear phases. The Goldreich-Levin algorithm can be viewed as an algorithmic analogue of such a decomposition as it ... more >>>


TR11-085 | 14th May 2011
Yijia Chen, Joerg Flum, Moritz Müller

Hard instances of algorithms and proof systems

Assuming that the class TAUT of tautologies of propositional logic has no almost optimal algorithm, we show that every algorithm $\mathbb A$ deciding TAUT has a polynomial time computable sequence witnessing that $\mathbb A$ is not almost optimal. The result extends to every $\Pi_t^p$-complete problem with $t\ge 1$; however, we ... more >>>


TR11-086 | 2nd June 2011
Masaki Yamamoto

A tighter lower bound on the circuit size of the hardest Boolean functions

In [IPL2005],
Frandsen and Miltersen improved bounds on the circuit size $L(n)$ of the hardest Boolean function on $n$ input bits:
for some constant $c>0$:
\[
\left(1+\frac{\log n}{n}-\frac{c}{n}\right)
\frac{2^n}{n}
\leq
L(n)
\leq
\left(1+3\frac{\log n}{n}+\frac{c}{n}\right)
\frac{2^n}{n}.
\]
In this note,
we announce a modest ... more >>>


TR11-087 | 3rd June 2011
Michael Viderman

A Combination of Testability and Decodability by Tensor Products

Revisions: 3

Ben-Sasson and Sudan (RSA 2006) showed that repeated tensor products of linear codes with a very large distance are locally testable. Due to the requirement of a very large distance the associated tensor products could be applied only over sufficiently large fields. Then Meir (SICOMP 2009) used this result (as ... more >>>


TR11-088 | 7th June 2011
Pavel Hrubes

How much commutativity is needed to prove polynomial identities?

Let $f$ be a non-commutative polynomial such that $f=0$ if we assume that the variables in $f$ commute. Let $Q(f)$ be the smallest $k$ such that there exist polynomials $g_1,g_1', g_2, g_2',\dots, g_k, g_k' $ with \[f\in I([g_1,g_1'], [g_2, g_2'],\dots, [g_k, g_k'] )\,,\]
where $[g,h]=gh-hg$. Then $Q(f)\leq {n\choose 2}$, where ... more >>>


TR11-089 | 7th June 2011
Paul Valiant

Distribution Free Evolvability of Polynomial Functions over all Convex Loss Functions

Revisions: 1

We formulate a notion of evolvability for functions with domain and range that are real-valued vectors, a compelling way of expressing many natural biological processes. We show that linear and fixed degree polynomial functions are evolvable in the following dually robust sense: There is a single evolution algorithm that for ... more >>>


TR11-090 | 2nd June 2011
Mahdi Cheraghchi, Adam Klivans, Pravesh Kothari, Homin Lee

Submodular Functions Are Noise Stable

Revisions: 2

We show that all non-negative submodular functions have high noise-stability. As a consequence, we obtain a polynomial-time learning algorithm for this class with respect to any product distribution on $\{-1,1\}^n$ (for any constant accuracy parameter $\epsilon$ ). Our algorithm also succeeds in the agnostic setting. Previous work on learning submodular ... more >>>


TR11-091 | 20th May 2011
Edward Hirsch, Dmitry Itsykson, Valeria Nikolaenko, Alexander Smal

Optimal heuristic algorithms for the image of an injective function

The existence of optimal algorithms is not known for any decision problem in NP$\setminus$P. We consider the problem of testing the membership in the image of an injective function. We construct optimal heuristic algorithms for this problem in both randomized and deterministic settings (a heuristic algorithm can err on a ... more >>>


TR11-092 | 2nd June 2011
Doerr Benjamin, Winzen Carola

Memory-Restricted Black-Box Complexity

We show that the black-box complexity with memory restriction one of the $n$-dimensional $\onemax$ function class is at most $2n$. This disproves the $\Theta(n \log n)$ conjecture of Droste, Jansen, and Wegener (Theory of Computing Systems 39 (2006) 525--544).

more >>>

TR11-093 | 8th June 2011
Pinyan Lu

Complexity Dichotomies of Counting Problems

In order to study the complexity of counting problems, several interesting frameworks have been proposed, such as Constraint Satisfaction Problems (#CSP) and Graph Homomorphisms. Recently, we proposed and explored a novel alternative framework, called Holant Problems. It is a refinement with a more explicit role for constraint functions. Both graph ... more >>>


TR11-094 | 20th June 2011
Shachar Lovett

Computing polynomials with few multiplications

A folklore result in arithmetic complexity shows that the number of multiplications required to compute some $n$-variate polynomial of degree $d$ is $\sqrt{{n+d \choose n}}$. We complement this by an almost matching upper bound, showing that any $n$-variate polynomial of degree $d$ over any field can be computed with only ... more >>>


TR11-095 | 22nd June 2011
Christoph Behle, Andreas Krebs, Klaus-Joern Lange, Pierre McKenzie

Low uniform versions of NC1

Revisions: 1

In the setting known as DLOGTIME-uniformity,
the fundamental complexity classes
$AC^0\subset ACC^0\subseteq TC^0\subseteq NC^1$ have several
robust characterizations.
In this paper we refine uniformity further and examine the impact
of these refinements on $NC^1$ and its subclasses.
When applied to the logarithmic circuit depth characterization of $NC^1$,
some refinements leave ... more >>>


TR11-096 | 2nd July 2011
Gil Cohen, Ran Raz, Gil Segev

Non-Malleable Extractors with Short Seeds and Applications to Privacy Amplification

Motivated by the classical problem of privacy amplification, Dodis and Wichs (STOC '09) introduced the notion of a non-malleable extractor, significantly strengthening the notion of a strong extractor. A non-malleable extractor is a function $nmExt : \{0,1\}^n \times \{0,1\}^d \rightarrow \{0,1\}^m$ that takes two inputs: a weak source $W$ and ... more >>>


TR11-097 | 7th July 2011
Thomas Watson

Lift-and-Project Integrality Gaps for the Traveling Salesperson Problem

Revisions: 1

We study the lift-and-project procedures of Lovasz-Schrijver and Sherali-Adams applied to the standard linear programming relaxation of the traveling salesperson problem with triangle inequality. For the asymmetric TSP tour problem, Charikar, Goemans, and Karloff (FOCS 2004) proved that the integrality gap of the standard relaxation is at least 2. We ... more >>>


TR11-098 | 11th July 2011
Marek Karpinski, Richard Schmied, Claus Viehmann

Tight Approximation Bounds for Vertex Cover on Dense k-Partite Hypergraphs

We establish almost tight upper and lower approximation bounds for the Vertex Cover problem on dense k-partite hypergraphs.

more >>>

TR11-099 | 11th July 2011
Anant Jindal, Gazal Kochar, Manjish Pal

Maximum Matchings via Glauber Dynamics

Revisions: 1 , Comments: 1

In this paper we study the classic problem of computing a maximum cardinality matching in general graphs $G = (V, E)$. This problem has been studied extensively more than four decades. The best known algorithm for this problem till date runs in $O(m \sqrt{n})$ time due to Micali and Vazirani ... more >>>


TR11-100 | 20th July 2011
Parikshit Gopalan, Cheng Huang, Huseyin Simitci, Sergey Yekhanin

On the Locality of Codeword Symbols

Consider a linear $[n,k,d]_q$ code $\mc{C}.$ We say that that $i$-th coordinate of $\mc{C}$ has locality $r,$ if the value at this coordinate can be recovered from accessing some other $r$ coordinates of $\mc{C}.$ Data storage applications require codes with small
redundancy, low locality for information coordinates, large distance, and ... more >>>


TR11-101 | 26th July 2011
Angsheng Li, Yicheng Pan, Pan Peng

Testing Conductance in General Graphs

In this paper, we study the problem of testing the conductance of a
given graph in the general graph model. Given distance parameter
$\varepsilon$ and any constant $\sigma>0$, there exists a tester
whose running time is $\mathcal{O}(\frac{m^{(1+\sigma)/2}\cdot\log
n\cdot\log\frac{1}{\varepsilon}}{\varepsilon\cdot\Phi^2})$, where
$n$ is the number of vertices and $m$ is the number ... more >>>


TR11-102 | 31st July 2011
Miklos Ajtai

Determinism Versus Nondeterminism with Arithmetic Tests and Computation

Revisions: 1

For each natural number $d$ we consider a finite structure $M_{d}$ whose
universe is the set of all $0,1$-sequence of length $n=2^{d}$, each
representing a natural number in the set $\lbrace 0,1,...,2^{n}-1\rbrace
$ in binary form.
The operations included in the structure are the
constants $0,1,2^{n}-1,n$, multiplication and addition ... more >>>


TR11-103 | 31st July 2011
Yang Li

BQP and PPAD

We initiate the study of the relationship between two complexity classes, BQP
(Bounded-Error Quantum Polynomial-Time) and PPAD (Polynomial Parity Argument,
Directed). We first give a conjecture that PPAD is contained in BQP, and show
a necessary and sufficient condition for the conjecture to hold. Then we prove
that the conjecture ... more >>>


TR11-104 | 3rd August 2011
Or Meir

Combinatorial PCPs with efficient verifiers

Revisions: 3

The PCP theorem asserts the existence of proofs that can be verified by a verifier that reads only a very small part of the proof. The theorem was originally proved by Arora and Safra (J. ACM 45(1)) and Arora et al. (J. ACM 45(3)) using sophisticated algebraic tools. More than ... more >>>


TR11-105 | 22nd July 2011
Graham Cormode, Michael Mitzenmacher, Justin Thaler

Streaming Graph Computations with a Helpful Advisor

Revisions: 1

Motivated by the trend to outsource work to commercial cloud computing services, we consider a variation of the streaming paradigm where a streaming algorithm can be assisted by a powerful helper that can provide annotations to the data stream. We extend previous work on such annotation models by considering a ... more >>>


TR11-106 | 6th August 2011
Andrew McGregor, Ilya Mironov, Toniann Pitassi, Omer Reingold, Kunal Talwar, Salil Vadhan

The Limits of Two-Party Differential Privacy

We study differential privacy in a distributed setting where two parties would like to perform analysis of their joint data while preserving privacy for both datasets. Our results imply almost tight lower bounds on the accuracy of such data analyses, both for specific natural functions (such as Hamming distance) and ... more >>>


TR11-107 | 22nd July 2011
Pavol Duris

On Computational Power of Partially Blind Automata

In this paper we deal with 1-way multihead finite automata, in which the symbol under only one head (called read head) controls its move and other heads cannot distinguish the input symbols, they can only distinguish the end-marker from the other input symbols and they are called the blind head. ... more >>>


TR11-108 | 8th August 2011
Scott Aaronson

Why Philosophers Should Care About Computational Complexity

Revisions: 2

One might think that, once we know something is computable, how efficiently it can be computed is a practical question with little further philosophical importance. In this essay, I offer a detailed case that one would be wrong. In particular, I argue that computational complexity theory---the field that studies the ... more >>>


TR11-109 | 9th August 2011
Zvika Brakerski, Vinod Vaikuntanathan

Efficient Fully Homomorphic Encryption from (Standard) LWE

We present a fully homomorphic encryption scheme that is based solely on the (standard) learning with errors (LWE) assumption. Applying known results on LWE, the security of our scheme is based on the worst-case hardness of ``short vector problems'' on arbitrary lattices.

Our construction improves on previous works in two ... more >>>


TR11-110 | 10th August 2011
Alessandro Chiesa, Michael Forbes

Improved Soundness for QMA with Multiple Provers

Revisions: 1

We present three contributions to the understanding of QMA with multiple provers:

1) We give a tight soundness analysis of the protocol of [Blier and Tapp, ICQNM '09], yielding a soundness gap $\Omega(N^{-2})$, which is the best-known soundness gap for two-prover QMA protocols with logarithmic proof size. Maybe ... more >>>


TR11-111 | 10th August 2011
Zvika Brakerski, Craig Gentry, Vinod Vaikuntanathan

Fully Homomorphic Encryption without Bootstrapping

We present a radically new approach to fully homomorphic encryption (FHE) that dramatically improves performance and bases security on weaker assumptions. A central conceptual contribution in our work is a new way of constructing leveled fully homomorphic encryption schemes (capable of evaluating arbitrary polynomial-size circuits), {\em without Gentry's bootstrapping procedure}.

... more >>>

TR11-112 | 10th August 2011
Dana Moshkovitz

The Projection Games Conjecture and The NP-Hardness of ln n-Approximating Set-Cover

In this paper we put forward a conjecture: an instantiation of the Sliding Scale Conjecture of Bellare, Goldwasser, Lund and Russell to projection games. We refer to this conjecture as the Projection Games Conjecture.

We further suggest the research agenda of establishing new hardness of approximation results based on the ... more >>>


TR11-113 | 11th August 2011
Emanuele Viola

Reducing 3XOR to listing triangles, an exposition

The 3SUM problem asks if there are three integers $a,b,c$ summing to $0$ in a given set of $n$ integers of magnitude poly($n$). Patrascu (STOC '10) reduces solving 3SUM in time $n^{2-\Omega(1)}$ to listing $m$ triangles in a graph with $m$ edges in time $m^{4/3-\Omega(1)}$.
In this note we present ... more >>>


TR11-114 | 8th August 2011
Varun Kanade

Computational Bottlenecks for Evolvability

Valiant (2007) proposed a computational model for evolution and suggested that evolvability be studied in the framework of computational learning theory. Feldman (2008) showed that Valiant’s evolution model is equivalent to the correlational statistical query (CSQ) learning model, which is a restricted setting of the statistical query (SQ) model. Evolvability ... more >>>


TR11-115 | 8th August 2011
Varun Kanade, Thomas Steinke

Learning Hurdles for Sleeping Experts

We study the online decision problem where the set of available actions varies over time, also called the sleeping experts problem. We consider the setting where the performance comparison is made with respect to the best ordering of actions in hindsight. In this paper, both the payoff function and the ... more >>>


TR11-116 | 17th August 2011
Andris Ambainis, Xiaoming Sun

New separation between $s(f)$ and $bs(f)$

In this note we give a new separation between sensitivity and block sensitivity of Boolean functions: $bs(f)=\frac{2}{3}s(f)^2-\frac{1}{3}s(f)$.

more >>>

TR11-117 | 3rd September 2011
Andrej Bogdanov, Periklis Papakonstantinou, Andrew Wan

Pseudorandomness for read-once formulas

We give an explicit construction of a pseudorandom generator for read-once formulas whose inputs can be read in arbitrary order. For formulas in $n$ inputs and arbitrary gates of fan-in at most $d = O(n/\log n)$, the pseudorandom generator uses $(1 - \Omega(1))n$ bits of randomness and produces an output ... more >>>


TR11-118 | 6th September 2011
Brett Hemenway, Rafail Ostrovsky, Martin Strauss, Mary Wootters

Public Key Locally Decodable Codes with Short Keys

This work considers locally decodable codes in the computationally bounded channel model. The computationally bounded channel model, introduced by Lipton in 1994, views the channel as an adversary which is restricted to polynomial-time computation. Assuming the existence of IND-CPA secure public-key encryption, we present a construction of public-key locally decodable ... more >>>


TR11-119 | 4th September 2011
Subhash Khot, Preyas Popat, Nisheeth Vishnoi

$2^{\log^{1-\epsilon} n}$ Hardness for Closest Vector Problem with Preprocessing

We prove that for an arbitrarily small constant $\eps>0,$ assuming NP$\not \subseteq$DTIME$(2^{{\log^{O(1/\epsilon)} n}})$, the preprocessing versions of the closest vector problem and the nearest codeword problem are hard to approximate within a factor better than $2^{\log ^{1-\epsilon}n}.$ This improves upon the previous hardness factor of $(\log n)^\delta$ for some $\delta ... more >>>


TR11-120 | 6th September 2011
Thomas Watson

Advice Lower Bounds for the Dense Model Theorem

Revisions: 1

We prove a lower bound on the amount of nonuniform advice needed by black-box reductions for the Dense Model Theorem of Green, Tao, and Ziegler, and of Reingold, Trevisan, Tulsiani, and Vadhan. The latter theorem roughly says that for every distribution $D$ that is $\delta$-dense in a distribution that is ... more >>>


TR11-121 | 12th September 2011
Oded Goldreich, Rani Izsak

Monotone Circuits: One-Way Functions versus Pseudorandom Generators

We study the computability of one-way functions and pseudorandom generators
by monotone circuits, showing a substantial gap between the two:
On one hand, there exist one-way functions that are computable
by (uniform) polynomial-size monotone functions, provided (of course)
that one-way functions exist at all.
On the other hand, ... more >>>


TR11-122 | 14th September 2011
Gillat Kol, Ran Raz

Competing Provers Protocols for Circuit Evaluation

Let $C$ be a (fan-in $2$) Boolean circuit of size $s$ and depth $d$, and let $x$ be an input for $C$. Assume that a verifier that knows $C$ but doesn't know $x$ can access the low degree extension of $x$ at one random point. Two competing provers try to ... more >>>


TR11-123 | 15th September 2011
Mark Braverman

Interactive information complexity

The primary goal of this paper is to define and study the interactive information complexity of functions. Let $f(x,y)$ be a function, and suppose Alice is given $x$ and Bob is given $y$. Informally, the interactive information complexity $IC(f)$ of $f$ is the least amount of information Alice and Bob ... more >>>


TR11-124 | 15th September 2011
Nader Bshouty, Hanna Mazzawi

Algorithms for the Coin Weighing Problems with the Presence of Noise

The coin weighing problem is the following: Given $n$ coins for which $m$ of them are counterfeit with the same weight. The problem is to detect the counterfeit coins with minimal number of weighings. This problem has many applications in compressed sensing, multiple access adder channels, etc. The problem was ... more >>>


TR11-125 | 16th September 2011
Andrew Drucker

Limitations of Lower-Bound Methods for the Wire Complexity of Boolean Operators

Revisions: 1 , Comments: 1

We study the circuit complexity of Boolean operators, i.e., collections of Boolean functions defined over a common input. Our focus is the well-studied model in which arbitrary Boolean functions are allowed as gates, and in which a circuit's complexity is measured by its depth and number of wires. We show ... more >>>


TR11-126 | 17th September 2011
Benny Applebaum, Andrej Bogdanov, Alon Rosen

A Dichotomy for Local Small-Bias Generators

We consider pseudorandom generators in which each output bit depends on a constant number of input bits. Such generators have appealingly simple structure: they can be described by a sparse input-output dependency graph and a small predicate that is applied at each output. Following the works of Cryan and Miltersen ... more >>>


TR11-127 | 18th September 2011
Ronen Shaltiel

Dispersers for affine sources with sub-polynomial entropy

We construct an explicit disperser for affine sources over $\F_2^n$ with entropy $k=2^{\log^{0.9} n}=n^{o(1)}$. This is a polynomial time computable function $D:\F_2^n \ar \B$ such that for every affine space $V$ of $\F_2^n$ that has dimension at least $k$, $D(V)=\set{0,1}$. This improves the best previous construction of Ben-Sasson and Kopparty ... more >>>


TR11-128 | 21st September 2011
Michael Elberfeld, Andreas Jakoby, Till Tantau

Algorithmic Meta Theorems for Circuit Classes of Constant and Logarithmic Depth

An algorithmic meta theorem for a logic and a class $C$ of structures states that all problems expressible in this logic can be solved efficiently for inputs from $C$. The prime example is Courcelle's Theorem, which states that monadic second-order (MSO) definable problems are linear-time solvable on graphs of bounded ... more >>>


TR11-129 | 22nd September 2011
Eli Ben-Sasson, Ariel Gabizon

Extractors for Polynomials Sources over Constant-Size Fields of Small Characteristic

Let $F$ be the field of $q$ elements, where $q=p^{\ell}$ for prime $p$. Informally speaking, a polynomial source is a distribution over $F^n$ sampled by low degree multivariate polynomials. In this paper, we construct extractors for polynomial sources over fields of constant size $q$ assuming $p \ll q$.

More generally, ... more >>>


TR11-130 | 25th September 2011
Sergei Lozhkin, Alexander Shiganov

On a Modification of Lupanov's Method with More Uniform Distribution of Fan-out

In this paper we suggest a modification of classical Lupanov's method [Lupanov1958]
that allows building circuits over the basis $\{\&,\vee,\neg\}$ for Boolean functions of $n$ variables with size at most
$$
\frac{2^n}{n}\left(1+\frac{3\log n + O(1)}{n}\right),
$$
and with more uniform distribution of outgoing arcs by circuit gates.

For almost all ... more >>>


TR11-131 | 29th September 2011
Rahul Santhanam, Srikanth Srinivasan

On the Limits of Sparsification

Impagliazzo, Paturi and Zane (JCSS 2001) proved a sparsification lemma for $k$-CNFs:
every k-CNF is a sub-exponential size disjunction of $k$-CNFs with a linear
number of clauses. This lemma has subsequently played a key role in the study
of the exact complexity of the satisfiability problem. A natural question is
more >>>


TR11-132 | 2nd September 2011
Ludwig Staiger

Oscillation-free Chaitin $h$-random sequences

Revisions: 1

The present paper generalises results by Tadaki [12] and Calude et al. [1] on oscillation-free partially random infinite strings. Moreover, it shows that oscillation-free partial Chaitin randomness can be separated from scillation-free partial strong Martin-L\"of randomness by $\Pi_{1}^{0}$-definable sets of infinite strings.

more >>>

TR11-133 | 4th October 2011
Maurice Jansen, Rahul Santhanam

Marginal Hitting Sets Imply Super-Polynomial Lower Bounds for Permanent

Suppose $f$ is a univariate polynomial of degree $r=r(n)$ that is computed by a size $n$ arithmetic circuit.
It is a basic fact of algebra that a nonzero univariate polynomial of degree $r$ can vanish on at most $r$ points. This implies that for checking whether $f$ is identically zero, ... more >>>


TR11-134 | 9th October 2011
Zeev Dvir, Guillaume Malod, Sylvain Perifel, Amir Yehudayoff

Separating multilinear branching programs and formulas

This work deals with the power of linear algebra in the context of multilinear computation. By linear algebra we mean algebraic branching programs (ABPs) which are known to be computationally equivalent to two basic tools in linear algebra: iterated matrix multiplication and the determinant. We compare the computational power of ... more >>>


TR11-135 | 9th October 2011
Maurice Jansen, Rahul Santhanam

Stronger Lower Bounds and Randomness-Hardness Tradeoffs using Associated Algebraic Complexity Classes

We associate to each Boolean language complexity class $\mathcal{C}$ the algebraic class $a\cdot\mathcal{C}$ consisting of families of polynomials $\{f_n\}$ for which the evaluation problem over the integers is in $\mathcal{C}$. We prove the following lower bound and randomness-to-hardness results:

1. If polynomial identity testing (PIT) is in $NSUBEXP$ then $a\cdot ... more >>>


TR11-136 | 12th October 2011
eran gat , shafi goldwasser

Probabilistic Search Algorithms with Unique Answers and Their Cryptographic Applications

Revisions: 1

In this paper we introduce a new type of probabilistic search algorithm, which we call the
{\it Bellagio} algorithm: a probabilistic algorithm which is guaranteed to run in expected polynomial time,
and to produce a correct and {\it unique} solution with high probability.
We argue the applicability of such algorithms ... more >>>


TR11-137 | 14th October 2011
Vikraman Arvind, Yadu Vasudev

Isomorphism Testing of Boolean Functions Computable by Constant Depth Circuits

Given two $n$-variable boolean functions $f$ and $g$, we study the problem of computing an $\varepsilon$-approximate isomorphism between them. I.e.\ a permutation $\pi$ of the $n$ variables such that $f(x_1,x_2,\ldots,x_n)$ and $g(x_{\pi(1)},x_{\pi(2)},\ldots,x_{\pi(n)})$ differ on at most an $\varepsilon$ fraction of all boolean inputs $\{0,1\}^n$. We give a randomized $2^{O(\sqrt{n}\log(n)^{O(1)})}$ algorithm ... more >>>


TR11-138 | 24th October 2011
Guy Moshkovitz

Complexity Lower Bounds through Balanced Graph Properties

In this paper we present a combinatorial approach for proving complexity lower bounds. We mainly focus on the following instantiation of it. Consider a pair of properties of $m$-edge regular hypergraphs. Suppose they are ``indistinguishable'' with respect to hypergraphs with $m-t$ edges, in the sense that every such hypergraph has ... more >>>


TR11-139 | 26th October 2011
Zeev Dvir, Shachar Lovett

Subspace Evasive Sets

In this work we describe an explicit, simple, construction of large subsets of F^n, where F is a finite field, that have small intersection with every k-dimensional affine subspace. Interest in the explicit construction of such sets, termed subspace-evasive sets, started in the work of Pudlak and Rodl (2004) ... more >>>


TR11-140 | 31st October 2011
Vikraman Arvind, Partha Mukhopadhyay, Prajakta Nimbhorkar, Yadu Vasudev

Expanding Generator Sets for Solvable Permutation Groups

Revisions: 1

Let $G=\langle S\rangle$ be a solvable permutation group given as input by generating set $S$. I.e.\ $G$ is a solvable subgroup of the symmetric group $S_n$. We give a deterministic polynomial-time algorithm that computes an expanding generator set for $G$. More precisely, given a constant $\lambda <1$ we can compute ... more >>>


TR11-141 | 2nd November 2011
Salil Vadhan, Colin Jia Zheng

Characterizing Pseudoentropy and Simplifying Pseudorandom Generator Constructions

Revisions: 3

We provide a characterization of pseudoentropy in terms of hardness of sampling: Let $(X,B)$ be jointly distributed random variables such that $B$ takes values in a polynomial-sized set. We show that $B$ is computationally indistinguishable from a random variable of higher Shannon entropy given $X$ if and only if there ... more >>>


TR11-142 | 2nd November 2011
Boaz Barak, Parikshit Gopalan, Johan Hastad, Raghu Meka, Prasad Raghavendra, David Steurer

Making the long code shorter, with applications to the Unique Games Conjecture

Revisions: 1

The long code is a central tool in hardness of approximation, especially in
questions related to the unique games conjecture. We construct a new code that
is exponentially more ecient, but can still be used in many of these applications.
Using the new code we obtain exponential improvements over several ... more >>>


TR11-143 | 2nd November 2011
Manindra Agrawal, Chandan Saha, Ramprasad Saptharishi, Nitin Saxena

Jacobian hits circuits: Hitting-sets, lower bounds for depth-D occur-k formulas & depth-3 transcendence degree-k circuits

We present a single, common tool to strictly subsume all known cases of polynomial time blackbox polynomial identity testing (PIT) that have been hitherto solved using diverse tools and techniques. In particular, we show that polynomial time hitting-set generators for identity testing of the two seemingly different and well studied ... more >>>


TR11-144 | 2nd November 2011
Greg Kuperberg, Shachar Lovett, Ron Peled

Probabilistic existence of rigid combinatorial structures

We show the existence of rigid combinatorial objects which previously were not known to exist. Specifically, for a wide range of the underlying parameters, we show the existence of non-trivial orthogonal arrays, $t$-designs, and $t$-wise permutations. In all cases, the sizes of the objects are optimal up to polynomial overhead. ... more >>>


TR11-145 | 2nd November 2011
Alexander A. Sherstov

The Multiparty Communication Complexity of Set Disjointness

We study the set disjointness problem in the number-on-the-forehead model.

(i) We prove that $k$-party set disjointness has randomized and nondeterministic
communication complexity $\Omega(n/4^k)^{1/4}$ and Merlin-Arthur complexity $\Omega(n/4^k)^{1/8}.$
These bounds are close to tight. Previous lower bounds (2007-2008) for $k\geq3$ parties
were weaker than $n^{1/(k+1)}/2^{k^2}$ in all ... more >>>


TR11-146 | 1st November 2011
Bireswar Das, Manjish Pal, Vijay Visavaliya

The Entropy Influence Conjecture Revisited

In this paper, we prove that most of the boolean functions, $f : \{-1,1\}^n \rightarrow \{-1,1\}$
satisfy the Fourier Entropy Influence (FEI) Conjecture due to Friedgut and Kalai (Proc. AMS'96)\cite{FG96}. The conjecture says that the Entropy of a boolean function is at most a constant times the Influence of ... more >>>


TR11-147 | 2nd November 2011
Michael Forbes, Amir Shpilka

On Identity Testing of Tensors, Low-rank Recovery and Compressed Sensing

We study the problem of obtaining efficient, deterministic, black-box polynomial identity testing algorithms for depth-3 set-multilinear circuits (over arbitrary fields). This class of circuits has an efficient, deterministic, white-box polynomial identity testing algorithm (due to Raz and Shpilka), but has no known such black-box algorithm. We recast this problem as ... more >>>


TR11-148 | 3rd November 2011
Rohit Gurjar, Arpita Korwar, Jochen Messner, Simon Straub, Thomas Thierauf

Planarizing Gadgets for Perfect Matching do not Exist

To compare the complexity of the perfect matching problem for general graphs with that for planar graphs, one might try to come up with a reduction from the perfect matching problem to the planar perfect matching problem.
The obvious way to construct such a reduction is via a {\em planarizing ... more >>>


TR11-149 | 4th November 2011
Paul Beame, Chris Beck, Russell Impagliazzo

Time-Space Tradeoffs in Resolution: Superpolynomial Lower Bounds for Superlinear Space

We give the first time-space tradeoff lower bounds for Resolution proofs that apply to superlinear space. In particular, we show that there are formulas of size $N$ that have Resolution refutations of space and size each roughly $N^{\log_2 N}$ (and like all formulas have Resolution refutations of space $N$) for ... more >>>


TR11-150 | 4th November 2011
Anna Gal, Kristoffer Arnsfelt Hansen, Michal Koucky, Pavel Pudlak, Emanuele Viola

Tight bounds on computing error-correcting codes by bounded-depth circuits with arbitrary gates

We bound the minimum number $w$ of wires needed to compute any (asymptotically good) error-correcting code
$C:\{0,1\}^{\Omega(n)} \to \{0,1\}^n$ with minimum distance $\Omega(n)$,
using unbounded fan-in circuits of depth $d$ with arbitrary gates. Our main results are:

(1) If $d=2$ then $w = \Theta(n ({\log n/ \log \log n})^2)$.

(2) ... more >>>


TR11-151 | 9th November 2011
Valentine Kabanets, Osamu Watanabe

Is the Valiant-Vazirani Isolation Lemma Improvable?

Revisions: 2

The Valiant-Vazirani Isolation Lemma [TCS, vol. 47, pp. 85--93, 1986] provides an efficient procedure for isolating a satisfying assignment of a given satisfiable circuit: given a Boolean circuit $C$ on $n$ input variables, the procedure outputs a new circuit $C'$ on the same $n$ input variables with the property that ... more >>>


TR11-152 | 12th November 2011
Emanuele Viola

The communication complexity of addition

Suppose each of $k \le n^{o(1)}$ players holds an $n$-bit number $x_i$ in its hand. The players wish to determine if $\sum_{i \le k} x_i = s$. We give a public-coin protocol with error $1\%$ and communication $O(k \lg k)$. The communication bound is independent of $n$, and for $k ... more >>>


TR11-153 | 13th November 2011
Ankit Gupta, Neeraj Kayal, Satyanarayana V. Lokam

Reconstruction of Depth-4 Multilinear Circuits with Top fanin 2

We present a randomized algorithm for reconstructing multilinear depth-4 arithmetic circuits with fan-in 2 at the top + gate. The algorithm is given blackbox access to a multilinear polynomial f in F[x_1,..,x_n] computable by a multilinear Sum-Product-Sum-Product(SPSP) circuit of size s and outputs an equivalent multilinear SPSP circuit, runs ... more >>>


TR11-154 | 17th November 2011
Klim Efremenko

From Irreducible Representations to Locally Decodable Codes

Locally Decodable Code (LDC) is a code that encodes a message in a way that one can decode any particular symbol of the message by reading only a constant number of locations, even if a constant fraction of the encoded message is adversarially
corrupted.

In this paper we ... more >>>


TR11-155 | 22nd November 2011
Anil Ada, Arkadev Chattopadhyay, Omar Fawzi, Phuong Nguyen

The NOF Multiparty Communication Complexity of Composed Functions

We study the $k$-party `number on the forehead' communication complexity of composed functions $f \circ \vec{g}$, where $f:\{0,1\}^n \to \{\pm 1\}$, $\vec{g} = (g_1,\ldots,g_n)$, $g_i : \{0,1\}^k \to \{0,1\}$ and for $(x_1,\ldots,x_k) \in (\{0,1\}^n)^k$, $f \circ \vec{g}(x_1,\ldots,x_k) = f(\ldots,g_i(x_{1,i},\ldots,x_{k,i}), \ldots)$. When $\vec{g} = (g,g,\ldots,g)$ we denote $f \circ \vec{g}$ by ... more >>>


TR11-156 | 23rd November 2011
Marek Karpinski, Richard Schmied

Improved Lower Bounds for the Shortest Superstring and Related Problems

Revisions: 1

We study the approximation hardness of the Shortest Superstring, the Maximal Compression and
the Maximum Asymmetric Traveling Salesperson (MAX-ATSP) problem.
We introduce a new reduction method that produces strongly restricted instances of
the Shortest Superstring problem, in which the maximal orbit size is eight
(with no ... more >>>


TR11-157 | 25th November 2011
Eli Ben-Sasson, Shachar Lovett, Noga Ron-Zewi

An additive combinatorics approach to the log-rank conjecture in communication complexity

Revisions: 1

For a {0,1}-valued matrix $M$ let CC($M$) denote the deterministic communication complexity of the boolean function associated with $M$. The log-rank conjecture of Lovasz and Saks [FOCS 1988] states that CC($M$) is at most $\log^c({\mbox{rank}}(M))$ for some absolute constant $c$ where rank($M$) denotes the rank of $M$ over the field ... more >>>


TR11-158 | 25th November 2011
Matthew Anderson, Dieter van Melkebeek, Nicole Schweikardt, Luc Segoufin

Locality from Circuit Lower Bounds

We study the locality of an extension of first-order logic that captures graph queries computable in AC$^0$, i.e., by families of polynomial-size constant-depth circuits. The extension considers first-order formulas over relational structures which may use arbitrary numerical predicates in such a way that their truth value is independent of the ... more >>>


TR11-159 | 27th November 2011
Oded Goldreich, Ron Rothblum

Enhancements of Trapdoor Permutations

Revisions: 1

We take a closer look at several enhancements of the notion of trapdoor permutations. Specifically, we consider the notions of enhanced trapdoor permutation (Goldreich 2004) and doubly enhanced trapdoor permutation (Goldreich 2008) as well as intermediate notions (Rothblum 2010). These enhancements arose in the study of Oblivious Transfer and NIZK, ... more >>>


TR11-160 | 1st December 2011
Zeev Dvir, Anup Rao, Avi Wigderson, Amir Yehudayoff

Restriction Access

We introduce a notion of non-black-box access to computational devices (such as circuits, formulas, decision trees, and so forth) that we call \emph{restriction access}. Restrictions are partial assignments to input variables. Each restriction simplifies the device, and yields a new device for the restricted function on the unassigned variables. On ... more >>>


TR11-161 | 4th December 2011
Xin Li

Design Extractors, Non-Malleable Condensers and Privacy Amplification

We introduce a new combinatorial object, called a \emph{design extractor}, that has both the properties of a design and an extractor. We give efficient constructions of such objects and show that they can be used in several applications.

\begin{enumerate}
\item {Improving the output length of known non-malleable extractors.} Non-malleable extractors ... more >>>


TR11-162 | 7th December 2011
Pavel Pudlak

A lower bound on the size of resolution proofs of the Ramsey theorem

We prove an exponential lower bound on the lengths of resolution proofs of propositions expressing the finite Ramsey theorem for pairs.

more >>>

TR11-163 | 2nd December 2011
Libor Barto, Marcin Kozik

Robust Satisfiability of Constraint Satisfaction Problems

An algorithm for a constraint satisfaction problem is called robust if it outputs an assignment satisfying at least $(1-g(\varepsilon))$-fraction of the constraints given a $(1-\varepsilon)$-satisfiable instance, where $g(\varepsilon) \rightarrow 0$ as $\varepsilon \rightarrow 0$, $g(0)=0$.
Guruswami and Zhou conjectured a characterization of constraint languages for which the corresponding constraint satisfaction ... more >>>


TR11-164 | 9th December 2011
Mark Braverman, Omri Weinstein

A discrepancy lower bound for information complexity

This paper provides the first general technique for proving information lower bounds on two-party
unbounded-rounds communication problems. We show that the discrepancy lower bound, which
applies to randomized communication complexity, also applies to information complexity. More
precisely, if the discrepancy of a two-party function $f$ with respect ... more >>>


TR11-165 | 8th December 2011
Elena Grigorescu, Chris Peikert

List Decoding Barnes-Wall Lattices

Revisions: 2

The question of list decoding error-correcting codes over finite fields (under the Hamming metric) has been widely studied in recent years. Motivated by the similar discrete structure of linear codes and point lattices in $R^{N}$, and their many shared applications across complexity theory, cryptography, and coding theory, we initiate the ... more >>>


TR11-166 | 4th December 2011
Xin Li

Non-Malleable Extractors for Entropy Rate $<1/2$

Revisions: 1

Dodis and Wichs \cite{DW09} introduced the notion of a non-malleable extractor to study the problem of privacy amplification with an active adversary. A non-malleable extractor is a much stronger version of a strong extractor. Given a weakly-random string $x$ and a uniformly random seed $y$ as the inputs, the non-malleable ... more >>>


TR11-167 | 6th December 2011
Nikolay Vereshchagin

Improving on Gutfreund, Shaltiel, and Ta-Shma's paper "If NP Languages are Hard on the Worst-Case, Then it is Easy to Find Their Hard Instances''

Revisions: 1

Assume that $NP\ne RP$. Gutfreund, Shaltiel, and Ta-Shma in [Computational Complexity 16(4):412-441 (2007)] have proved that for every randomized polynomial time decision algorithm $D$ for SAT there is a polynomial time samplable distribution such that $D$ errs with probability at least $1/6-\epsilon$ on a random formula chosen with respect to ... more >>>


TR11-168 | 9th December 2011
Joshua Grochow

Lie algebra conjugacy

We study the problem of matrix Lie algebra conjugacy. Lie algebras arise centrally in areas as diverse as differential equations, particle physics, group theory, and the Mulmuley--Sohoni Geometric Complexity Theory program. A matrix Lie algebra is a set $\mathcal{L}$ of matrices such that $A,B \in \mathcal{L}$ implies$AB - BA \in ... more >>>


TR11-169 | 14th December 2011
Leonid Gurvits

Unleashing the power of Schrijver's permanental inequality with the help of the Bethe Approximation

Revisions: 2

Let $A \in \Omega_n$ be doubly-stochastic $n \times n$ matrix. Alexander Schrijver proved in 1998 the following remarkable inequality
\begin{equation} \label{le}
per(\widetilde{A}) \geq \prod_{1 \leq i,j \leq n} (1- A(i,j)); \widetilde{A}(i,j) =: A(i,j)(1-A(i,j)), 1 \leq i,j \leq n
\end{equation}
We prove in this paper the following generalization (or just clever ... more >>>


TR11-170 | 16th December 2011
Constantinos Daskalakis, S. Matthew Weinberg

On Optimal Multi-Dimensional Mechanism Design

We efficiently solve the optimal multi-dimensional mechanism design problem for independent bidders with arbitrary demand constraints when either the number of bidders is a constant or the number of items is a constant. In the first setting, we need that each bidder's values for the items are sampled from a ... more >>>


TR11-171 | 15th December 2011
Piotr Indyk, Reut Levi, Ronitt Rubinfeld

Approximating and Testing $k$-Histogram Distributions in Sub-linear time

Revisions: 1

A discrete distribution $p$, over $[n]$, is a $k$-histogram if its probability distribution function can be
represented as a piece-wise constant function with $k$ pieces. Such a function
is
represented by a list of $k$ intervals and $k$ corresponding values. We consider
the following problem: given a collection of samples ... more >>>


TR11-172 | 20th December 2011
Yang Cai, Constantinos Daskalakis, S. Matthew Weinberg

An Algorithmic Characterization of Multi-Dimensional Mechanisms

We obtain a characterization of feasible, Bayesian, multi-item multi-bidder mechanisms with independent, additive bidders as distributions over hierarchical mechanisms. Combined with cyclic-monotonicity our results provide a complete characterization of feasible, Bayesian Incentive Compatible mechanisms for this setting.

Our characterization is enabled by a novel, constructive proof of Border's theorem [Border ... more >>>


TR11-173 | 22nd December 2011
Christoph Behle, Andreas Krebs

Regular Languages in MAJ[<] with three variables

We consider first order logic over words and show FO+MOD[<] is contained in MAJ[<] with three variables.
It is known that for the classes FO[<], FO+MOD[<], FO+GROUP[<] three variables suffice. In the case of MOD[<] even two variables are sufficient.

As a consequence we know that if TC^ 0 neq ... more >>>


TR11-174 | 30th December 2011
Pavel Hrubes, Iddo Tzameret

Short Proofs for the Determinant Identities

Revisions: 1

We study arithmetic proof systems $\mathbb{P}_c(\mathbb{F})$ and $\mathbb{P}_f(\mathbb{F})$ operating with arithmetic circuits and arithmetic formulas, respectively, that prove polynomial identities over a field $\mathbb{F}$. We establish a series of structural theorems about these proof systems, the main one stating that $\mathbb{P}_c(\mathbb{F})$ proofs can be balanced: if a polynomial identity of ... more >>>




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