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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 >>>


TR17-117 | 20th July 2017
Dmitry Itsykson, Alexander Knop

Hard satisfiable formulas for splittings by linear combinations

Itsykson and Sokolov in 2014 introduced the class of DPLL($\oplus$) algorithms that solve Boolean satisfiability problem using the splitting by linear combinations of variables modulo 2. This class extends the class of DPLL algorithms that split by variables. DPLL($\oplus$) algorithms solve in polynomial time systems of linear equations modulo two ... more >>>


TR13-151 | 7th November 2013
Mark Bun, Justin Thaler

Hardness Amplification and the Approximate Degree of Constant-Depth Circuits

Revisions: 3

We establish a generic form of hardness amplification for the approximability of constant-depth Boolean circuits by polynomials. Specifically, we show that if a Boolean circuit cannot be pointwise approximated by low-degree polynomials to within constant error in a certain one-sided sense, then an OR of disjoint copies of that circuit ... more >>>


TR07-102 | 4th October 2007
Andrej Bogdanov, Muli Safra

Hardness amplification for errorless heuristics

An errorless heuristic is an algorithm that on all inputs returns either the correct answer or the special symbol "I don't know." A central question in average-case complexity is whether every distributional decision problem in NP has an errorless heuristic scheme: This is an algorithm that, for every δ > ... more >>>


TR09-072 | 3rd September 2009
Paul Beame, Trinh Huynh

Hardness Amplification in Proof Complexity

Revisions: 2 , Comments: 2

We present a generic method for converting any family of unsatisfiable CNF formulas that require large resolution rank into CNF formulas whose refutation requires large rank for proof systems that manipulate polynomials or polynomial threshold functions of degree at most $k$ (known as ${\rm Th}(k)$ proofs). Such systems include: Lovasz-Schrijver ... more >>>


TR07-130 | 3rd December 2007
Ronen Shaltiel, Emanuele Viola

Hardness amplification proofs require majority

Hardness amplification is the fundamental task of
converting a $\delta$-hard function $f : {0,1}^n ->
{0,1}$ into a $(1/2-\eps)$-hard function $Amp(f)$,
where $f$ is $\gamma$-hard if small circuits fail to
compute $f$ on at least a $\gamma$ fraction of the
inputs. Typically, $\eps,\delta$ are small (and
$\delta=2^{-k}$ captures the case ... more >>>


TR05-057 | 19th May 2005
Venkatesan Guruswami, Valentine Kabanets

Hardness amplification via space-efficient direct products

We prove a version of the derandomized Direct Product Lemma for
deterministic space-bounded algorithms. Suppose a Boolean function
$g:\{0,1\}^n\to\{0,1\}$ cannot be computed on more than $1-\delta$
fraction of inputs by any deterministic time $T$ and space $S$
algorithm, where $\delta\leq 1/t$ for some $t$. Then, for $t$-step
walks $w=(v_1,\dots, v_t)$ ... 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 >>>


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 >>>


TR06-071 | 25th April 2006
John Hitchcock, A. Pavan

Hardness Hypotheses, Derandomization, and Circuit Complexity

We consider hypotheses about nondeterministic computation that
have been studied in different contexts and shown to have interesting
consequences:

1. The measure hypothesis: NP does not have p-measure 0.

2. The pseudo-NP hypothesis: there is an NP language that can be
distinguished from any DTIME(2^n^epsilon) language by an ... more >>>


TR09-112 | 3rd November 2009
Davide Bilò, Luciano Gualà, Guido Proietti

Hardness of an Asymmetric 2-player Stackelberg Network Pricing Game

Consider a communication network represented by a directed graph $G=(V,E)$ of $n$ nodes and $m$ edges. Assume that edges in $E$ are
partitioned into two sets: a set $C$ of edges with a fixed
non-negative real cost, and a set $P$ of edges whose \emph{price} should instead be set by ... more >>>


TR00-062 | 25th August 2000
Venkatesan Guruswami, Johan Hastad, Madhu Sudan

Hardness of approximate hypergraph coloring

We introduce the notion of covering complexity of a probabilistic
verifier. The covering complexity of a verifier on a given input is
the minimum number of proofs needed to ``satisfy'' the verifier on
every random string, i.e., on every random string, at least one of the
given proofs must be ... more >>>


TR05-127 | 5th November 2005
Vitaly Feldman

Hardness of Approximate Two-level Logic Minimization and PAC Learning with Membership Queries

Revisions: 1

Producing a small DNF expression consistent with given data is a
classical problem in computer science that occurs in a number of forms and
has numerous applications. We consider two standard variants of this
problem. The first one is two-level logic minimization or finding a minimal
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 >>>


TR99-029 | 31st August 1999
Ilya Dumer, Daniele Micciancio, Madhu Sudan

Hardness of approximating the minimum distance of a linear code

We show that the minimum distance of a linear code (or
equivalently, the weight of the lightest codeword) is
not approximable to within any constant factor in random polynomial
time (RP), unless NP equals RP.
Under the stronger assumption that NP is not contained in RQP
(random ... more >>>


TR06-019 | 24th November 2005
Janka Chlebíková, Miroslav Chlebík

Hardness of asymptotic approximation for orthogonal rectangle packing and covering problems

Recently Bansal and Sviridenko (Proc. of the 15th SODA'04, 189-196)
proved that for
2-dimensional Orthogonal Rectangle
Bin Packing without rotations allowed there is no asymptotic PTAS, unless P=NP. We show that similar
approximation hardness results hold for several rectangle packing and covering problems even if rotations by ninety
more >>>


TR14-051 | 12th April 2014
Subhash Khot, Rishi Saket

Hardness of Coloring $2$-Colorable $12$-Uniform Hypergraphs with $2^{(\log n)^{\Omega(1)}}$ Colors

We show that it is quasi-NP-hard to color $2$-colorable $12$-uniform hypergraphs with $2^{(\log n)^{\Omega(1) }}$ colors where $n$ is the number of vertices. Previously, Guruswami et al. [GHHSV14] showed that it is quasi-NP-hard to color $2$-colorable $8$-uniform hypergraphs with $2^{2^{\Omega(\sqrt{\log \log n})}}$ colors. Their result is obtained by composing a ... more >>>


TR16-063 | 18th April 2016
Pavel Hubacek, Eylon Yogev

Hardness of Continuous Local Search: Query Complexity and Cryptographic Lower Bounds

Revisions: 1

Local search proved to be an extremely useful tool when facing hard optimization problems (e.g. via the simplex algorithm, simulated annealing, or genetic algorithms). Although powerful, it has its limitations: there are functions for which exponentially many queries are needed to find a local optimum. In many contexts the optimization ... more >>>


TR06-109 | 29th August 2006
Julia Chuzhoy, Sanjeev Khanna

Hardness of Directed Routing with Congestion

Given a graph G and a collection of source-sink pairs in G, what is the least integer c such that each source can be connected by a path to its sink, with at most c paths going through an edge? This is known as the congestion minimization problem, and the ... more >>>


TR06-061 | 5th May 2006
Venkatesan Guruswami, Prasad Raghavendra

Hardness of Learning Halfspaces with Noise

Learning an unknown halfspace (also called a perceptron) from
labeled examples is one of the classic problems in machine learning.
In the noise-free case, when a halfspace consistent with all the
training examples exists, the problem can be solved in polynomial
time using linear programming. ... more >>>


TR17-115 | 5th July 2017
Arnab Bhattacharyya, Suprovat Ghoshal, Rishi Saket

Hardness of learning noisy halfspaces using polynomial thresholds

We prove the hardness of weakly learning halfspaces in the presence of adversarial noise using polynomial threshold functions (PTFs). In particular, we prove that for any constants $d \in \mathbb{Z}^+$ and $\epsilon > 0$, it is NP-hard to decide: given a set of $\{-1,1\}$-labeled points in $\mathbb{R}^n$ whether (YES Case) ... more >>>


TR06-141 | 22nd November 2006
Venkatesan Guruswami, Kunal Talwar

Hardness of Low Congestion Routing in Directed Graphs

We prove a strong inapproximability result for routing on directed
graphs with low congestion. Given as input a directed graph on $N$
vertices and a set of source-destination pairs that can be connected
via edge-disjoint paths, we prove that it is hard, assuming NP
doesn't have $n^{O(\log\log n)}$ time randomized ... 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 >>>


TR17-147 | 3rd October 2017
Venkatesan Guruswami, Rishi Saket

Hardness of Rainbow Coloring Hypergraphs

A hypergraph is $k$-rainbow colorable if there exists a vertex coloring using $k$ colors such that each hyperedge has all the $k$ colors. Unlike usual hypergraph coloring, rainbow coloring becomes harder as the number of colors increases. This work studies the rainbow colorability of hypergraphs which are guaranteed to be ... more >>>


TR07-073 | 3rd August 2007
Parikshit Gopalan, Subhash Khot, Rishi Saket

Hardness of Reconstructing Multivariate Polynomials over Finite Fields

We study the polynomial reconstruction problem for low-degree
multivariate polynomials over finite fields. In the GF[2] version of this problem, we are given a set of points on the hypercube and target values $f(x)$ for each of these points, with the promise that there is a polynomial over GF[2] of ... more >>>


TR09-020 | 2nd March 2009
Venkatesan Guruswami, Prasad Raghavendra

Hardness of Solving Sparse Overdetermined Linear Systems: A 3-Query PCP over Integers.

A classic result due to Hastad established that for every constant \eps > 0, given an overdetermined system of linear equations over a finite field \F_q where each equation depends on exactly 3 variables and at least a fraction (1-\eps) of the equations can be satisfied, it is NP-hard to ... more >>>


TR12-182 | 24th December 2012
Itay Berman, Iftach Haitner, Ilan Komargodski, Moni Naor

Hardness Preserving Reductions via Cuckoo Hashing

Revisions: 2

A common method for increasing the usability and uplifting the security of pseudorandom function families (PRFs) is to ``hash" the inputs into a smaller domain before applying the PRF. This approach, known as ``Levin's trick", is used to achieve ``PRF domain extension" (using a short, e.g., fixed, input length PRF ... more >>>


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

Hardness-Randomness Tradeoffs for Bounded Depth Arithmetic Circuits

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


TR04-072 | 19th August 2004
John Hitchcock

Hausdorff Dimension and Oracle Constructions

Bennett and Gill (1981) proved that P^A != NP^A relative to a
random oracle A, or in other words, that the set
O_[P=NP] = { A | P^A = NP^A }
has Lebesgue measure 0. In contrast, we show that O_[P=NP] has
Hausdorff dimension 1.

... more >>>


TR03-034 | 17th March 2003
Arnold Beckmann

Height restricted constant depth LK

Height restricted constant depth LK is a natural restriction of
Gentzen's propositional proof system LK. A sequence of LK-formulas
has polylogarithmic-height restricted depth-d-LK proofs iff the
n-th formula in the sequence possesses LK-proofs where cut-formulas
are of depth d+1 with small bottom fanin
and of ... more >>>


TR13-074 | 9th May 2013
Johannes Köbler, Sebastian Kuhnert, Oleg Verbitsky

Helly Circular-Arc Graph Isomorphism is in Logspace

We present logspace algorithms for the canonical labeling problem and the representation problem of Helly circular-arc (HCA) graphs. The first step is a reduction to canonical labeling and representation of interval intersection matrices. In a second step, the Delta trees employed in McConnell's linear time representation algorithm for interval matrices ... more >>>


TR14-178 | 5th December 2014
Dmitry Itsykson, Alexander Knop, Dmitry Sokolov

Heuristic time hierarchies via hierarchies for sampling distributions

We give a new simple proof of the time hierarchy theorem for heuristic BPP originally proved by Fortnow and Santhanam [FS04] and then simplified and improved by Pervyshev [P07]. In the proof we use a hierarchy theorem for sampling distributions recently proved by Watson [W13]. As a byproduct we get ... more >>>


TR14-171 | 11th December 2014
Lance Fortnow, Rahul Santhanam

Hierarchies Against Sublinear Advice

We strengthen the non-deterministic time hierarchy theorem of
\cite{Cook72, Seiferas-Fischer-Meyer78, Zak83} to show that the lower bound
holds against sublinear advice. More formally, we show that for any constants
$c$ and $d$ such that $1 \leq c < d$, there is a language in $\NTIME(n^d)$
which is not in $\NTIME(n^c)/n^{1/d}$. ... more >>>


TR08-097 | 14th November 2008
Oded Goldreich, Michael Krivelevich, Ilan Newman, Eyal Rozenberg

Hierarchy Theorems for Property Testing

Revisions: 1

Referring to the query complexity of property testing,
we prove the existence of a rich hierarchy of corresponding
complexity classes. That is, for any relevant function $q$,
we prove the existence of properties that have testing
complexity Theta(q).
Such results are proven in three standard
domains often considered in property ... more >>>


TR17-157 | 13th October 2017
Monaldo Mastrolilli

High Degree Sum of Squares Proofs, Bienstock-Zuckerberg hierarchy and Chvatal-Gomory cuts

Revisions: 1

Chvatal-Gomory (CG) cuts and the Bienstock-Zuckerberg hierarchy capture useful linear programs that the standard bounded degree Lasserre/Sum-of-Squares (SOS) hierarchy fails to capture.

In this paper we present a novel polynomial time SOS hierarchy for 0/1 problems with a custom subspace of high degree polynomials (not the standard subspace of low-degree ... more >>>


TR17-089 | 11th May 2017
Irit Dinur, Tali Kaufman

High dimensional expanders imply agreement expanders

We show that high dimensional expanders imply derandomized direct product tests, with a number of subsets that is *linear* in the size of the universe.

Direct product tests belong to a family of tests called agreement tests that are important components in PCP constructions and include, for example, low degree ... more >>>


TR13-053 | 4th April 2013
Alan Guo

High rate locally correctable codes via lifting

Revisions: 1

We present a general framework for constructing high rate error correcting codes that are locally correctable (and hence locally decodable if linear) with a sublinear number of queries, based on lifting codes with respect to functions on the coordinates. Our approach generalizes the lifting of affine-invariant codes of Guo, Kopparty, ... more >>>


TR15-068 | 21st April 2015
Swastik Kopparty, Noga Ron-Zewi, Shubhangi Saraf

High rate locally-correctable and locally-testable codes with sub-polynomial query complexity

Revisions: 2

In this work, we construct the first locally-correctable codes (LCCs), and locally-testable codes (LTCs) with constant rate, constant relative distance, and sub-polynomial query complexity. Specifically, we show that there exist binary LCCs and LTCs with block length $n$, constant rate (which can even be taken arbitrarily close to 1), constant ... 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 >>>


TR15-110 | 8th July 2015
Swastik Kopparty, Or Meir, Noga Ron-Zewi, Shubhangi Saraf

High-rate Locally-testable Codes with Quasi-polylogarithmic Query Complexity

Revisions: 1

An error correcting code is said to be \emph{locally testable} if
there is a test that checks whether a given string is a codeword,
or rather far from the code, by reading only a small number of symbols
of the string. Locally testable codes (LTCs) are both interesting
in their ... 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 >>>


TR96-055 | 22nd October 1996
Alexander E. Andreev, Andrea E. F. Clementi, Jose' D. P. Rolim

Hitting Properties of Hard Boolean Operators and their Consequences on BPP

Revisions: 1 , Comments: 1

We present the first worst-case hardness conditions
on the circuit complexity of EXP functions which are
sufficient to obtain P=BPP. In particular, we show that
from such hardness conditions it is possible to construct
quick Hitting Sets Generators with logarithmic prize.
... more >>>


TR95-061 | 27th November 1995
Alexander E. Andreev, Andrea E. F. Clementi, Jose' D. P. Rolim

Hitting sets derandomize BPP

Revisions: 1

We show that hitting sets can derandomize any BPP-algorithm.
This gives a positive answer to a fundamental open question in
probabilistic algorithms. More precisely, we present a polynomial
time deterministic algorithm which uses any given hitting set
to approximate the fractions of 1's in the ... more >>>


TR13-175 | 6th December 2013
Venkatesan Guruswami, Chaoping Xing

Hitting Sets for Low-Degree Polynomials with Optimal Density

Revisions: 1

We give a length-efficient puncturing of Reed-Muller codes which preserves its distance properties. Formally, for the Reed-Muller code encoding $n$-variate degree-$d$ polynomials over ${\mathbb F}_q$ with $q \ge \Omega(d/\delta)$, we present an explicit (multi)-set $S \subseteq {\mathbb F}_q^n$ of size $N=\mathrm{poly}(n^d/\delta)$ such that every nonzero polynomial vanishes on at most ... more >>>


TR17-161 | 30th October 2017
Mark Braverman, Gil Cohen, Sumegha Garg

Hitting Sets with Near-Optimal Error for Read-Once Branching Programs

Nisan (Combinatorica'92) constructed a pseudorandom generator for length $n$, width $n$ read-once branching programs (ROBPs) with error $\varepsilon$ and seed length $O(\log^2{n} + \log{n} \cdot \log(1/\varepsilon))$. A major goal in complexity theory is to reduce the seed length, hopefully, to the optimal $O(\log{n}+\log(1/\varepsilon))$, or to construct improved hitting sets, as ... more >>>


TR13-174 | 6th December 2013
Manindra Agrawal, Rohit Gurjar, Arpita Korwar, Nitin Saxena

Hitting-sets for low-distance multilinear depth-$3$

The depth-$3$ model has recently gained much importance, as it has become a stepping-stone to understanding general arithmetic circuits. Its restriction to multilinearity has known exponential lower bounds but no nontrivial blackbox identity tests. In this paper we take a step towards designing such hitting-sets. We define a notion of ... more >>>


TR14-085 | 29th June 2014
Manindra Agrawal, Rohit Gurjar, Arpita Korwar, Nitin Saxena

Hitting-sets for ROABP and Sum of Set-Multilinear circuits

We give a $n^{O(\log n)}$-time ($n$ is the input size) blackbox polynomial identity testing algorithm for unknown-order read-once oblivious algebraic branching programs (ROABP). The best time-complexity known for this class was $n^{O(\log^2 n)}$ due to Forbes-Saptharishi-Shpilka (STOC 2014), and that too only for multilinear ROABP. We get rid of their ... more >>>


TR05-099 | 9th September 2005
Leslie G. Valiant

Holographic Algorithms

Complexity theory is built fundamentally on the notion of efficient
reduction among computational problems. Classical
reductions involve gadgets that map solution fragments of one problem to
solution fragments of another in one-to-one, or
possibly one-to-many, fashion. In this paper we propose a new kind of
reduction that allows for gadgets ... more >>>


TR06-145 | 1st December 2006
Jin-Yi Cai, Pinyan Lu

Holographic Algorithms: From Art to Science

We develop the theory of holographic algorithms. We give
characterizations of algebraic varieties of realizable
symmetric generators and recognizers on the basis manifold,
and a polynomial time decision algorithm for the
simultaneous realizability problem.
Using the general machinery we are able to give
unexpected holographic algorithms for
some counting problems, ... more >>>


TR07-020 | 11th March 2007
Jin-Yi Cai, Pinyan Lu

Holographic Algorithms: The Power of Dimensionality Resolved

Valiant's theory of holographic algorithms is a novel methodology
to achieve exponential speed-ups in computation. A fundamental
parameter in holographic algorithms is the dimension of the linear basis
vectors.
We completely resolve the problem of the power of higher dimensional
bases. We prove that 2-dimensional bases are universal for
holographic ... 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 >>>


TR14-163 | 29th November 2014
Arnaud Durand, Meena Mahajan, Guillaume Malod, Nicolas de Rugy-Altherre, Nitin Saurabh

Homomorphism polynomials complete for VP

The VP versus VNP question, introduced by Valiant, is probably the most important open question in algebraic complexity theory. Thanks to completeness results, a variant of this question, VBP versus VNP, can be succinctly restated as asking whether the permanent of a generic matrix can be written as a determinant ... more >>>


TR05-085 | 5th August 2005
Asaf Shapira, Noga Alon

Homomorphisms in Graph Property Testing - A Survey

Property-testers are fast randomized algorithms for distinguishing
between graphs (and other combinatorial structures) satisfying a
certain property, from those that are far from satisfying it. In
many cases one can design property-testers whose running time is in
fact {\em independent} of the size of the input. In this paper we
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 >>>


TR12-167 | 16th November 2012
Periklis Papakonstantinou, Charles Rackoff, Yevgeniy Vahlis

How powerful are the DDH hard groups?

The question whether Identity-Based Encryption (IBE) can be based on the Decisional Diffie-Hellman (DDH) assumption is one of the most prominent questions in Cryptography related to DDH. We study limitations on the use of the DDH assumption in cryptographic constructions, and show that it is impossible to construct a secure ... more >>>


TR17-100 | 7th June 2017
Dakshita Khurana, Amit Sahai

How to Achieve Non-Malleability in One or Two Rounds

Despite over 25 years of research on non-malleable commitments in the plain model, their round complexity has remained open. The goal of achieving non-malleable commitment protocols with only one or two rounds has been especially elusive. Pass (TCC 2013, CC 2016) captured this difficulty by proving important impossibility results regarding ... more >>>


TR09-132 | 8th December 2009
Lior Malka

How to Achieve Perfect Simulation and a Complete Problem for Non-interactive Perfect Zero-Knowledge

Perfect zero-knowledge (PZK) proofs have been constructed in various settings and they are
also interesting from a complexity theoretic perspective. Yet, virtually nothing is known about them. This is in contrast to statistical zero-knowledge proofs, where many general results have been proved using an array of tools, none of which ... more >>>


TR15-055 | 13th April 2015
Sivaramakrishnan Natarajan Ramamoorthy, Anup Rao

How to Compress Asymmetric Communication

We study the relationship between communication and information in 2-party communication protocols when the information is asymmetric. If $I^A$ denotes the number of bits of information revealed by the first party, $I^B$ denotes the information revealed by the second party, and $C$ is the number of bits of communication in ... more >>>


TR12-010 | 5th February 2012
Shafi Goldwasser, Guy Rothblum

How to Compute in the Presence of Leakage

We address the following problem: how to execute any algorithm P, for an unbounded number of executions, in the presence of an adversary who observes partial information on the internal state of the computation during executions. The security guarantee is that the adversary learns nothing, beyond P's input/output behavior.

This ... more >>>


TR12-140 | 27th October 2012
Mark Zhandry

How to Construct Quantum Random Functions

Revisions: 2

In the presence of a quantum adversary, there are two possible definitions of security for a pseudorandom function. The first, which we call standard-security, allows the adversary to be quantum, but requires queries to the function to be classical. The second, quantum-security, allows the adversary to query the function on ... more >>>


TR13-183 | 22nd December 2013
Yael Tauman Kalai, Ran Raz, Ron Rothblum

How to Delegate Computations: The Power of No-Signaling Proofs

Revisions: 1

We construct a 1-round delegation scheme (i.e., argument-system) for every language computable in time t=t(n), where the running time of the prover is poly(t) and the running time of the verifier is n*polylog(t). In particular, for every language in P we obtain a delegation scheme with almost linear time verification. ... more >>>


TR12-058 | 5th May 2012
Benny Applebaum, Yuval Ishai, Eyal Kushilevitz

How to Garble Arithmetic Circuits

Revisions: 1

Yao's garbled circuit construction transforms a boolean circuit $C:\{0,1\}^n\to\{0,1\}^m$
into a ``garbled circuit'' $\hat{C}$ along with $n$ pairs of $k$-bit keys, one for each
input bit, such that $\hat{C}$ together with the $n$ keys
corresponding to an input $x$ reveal $C(x)$ and no additional information about $x$.
The garbled circuit ... more >>>


TR05-145 | 5th December 2005
Ronen Shaltiel

How to get more mileage from randomness extractors

Let $\cal C$ be a class of distributions over $\B^n$. A deterministic randomness extractor for $\cal C$ is a function $E:\B^n \ar \B^m$ such that for any $X$ in $\cal C$ the distribution $E(X)$ is statistically close to the uniform distribution. A long line of research deals with explicit constructions ... more >>>


TR05-096 | 26th August 2005
Boaz Barak, Amit Sahai

How To Play Almost Any Mental Game Over The Net --- Concurrent Composition via Super-Polynomial Simulation

We construct a secure protocol for any multi-party functionality
that remains secure (under a relaxed definition of security) when
executed concurrently with multiple copies of itself and other
protocols. We stress that we do *not* use any assumptions on
existence of trusted parties, common reference string, honest
majority or synchronicity ... more >>>


TR09-021 | 2nd March 2009
Konstantin Makarychev, Yury Makarychev

How to Play Unique Games on Expanders

In this note we improve a recent result by Arora, Khot, Kolla, Steurer, Tulsiani, and Vishnoi on solving the Unique Games problem on expanders.

Given a (1 - epsilon)-satisfiable instance of Unique Games with the constraint graph G, our algorithm finds an assignments satisfying at least a (1 - C ... more >>>


TR06-144 | 21st November 2006
Claire Kenyon-Mathieu, Warren Schudy

How to rank with few errors: A PTAS for Weighted Feedback Arc Set on Tournaments

Suppose you ran a chess tournament, everybody played everybody, and you wanted to use the results to rank everybody. Unless you were really lucky, the results would not be acyclic, so you could not just sort the players by who beat whom. A natural objective is to find a ranking ... more >>>


TR16-023 | 23rd February 2016
Ilan Komargodski, Moni Naor, Eylon Yogev

How to Share a Secret, Infinitely

Revisions: 3

Secret sharing schemes allow a dealer to distribute a secret piece of information among several parties so that any qualified subset of parties can reconstruct the secret, while every unqualified subset of parties learns nothing about the secret. The collection of qualified subsets is called an access structure. The best ... more >>>


TR17-112 | 27th June 2017
Yehuda Lindell

How To Simulate It -- A Tutorial on the Simulation Proof Technique

One of the most fundamental notions of cryptography is that of \emph{simulation}. It stands behind the concepts of semantic security, zero knowledge, and security for multiparty computation. However, writing a simulator and proving security via the use of simulation is a non-trivial task, and one that many newcomers to the ... more >>>


TR06-025 | 19th January 2006
Leonid Gurvits

Hyperbolic Polynomials Approach to Van der Waerden/Schrijver-Valiant like Conjectures :\\ Sharper Bounds , Simpler Proofs and Algorithmic Applications

Let $p(x_1,...,x_n) = p(X) , X \in R^{n}$ be a homogeneous polynomial of degree $n$ in $n$ real variables ,
$e = (1,1,..,1) \in R^n$ be a vector of all ones . Such polynomial $p$ is
called $e$-hyperbolic if for all real vectors $X \in R^{n}$ the univariate polynomial
equation ... more >>>




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