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Electronic Colloquium on Computational Complexity

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All reports by Author Dmitry Gavinsky:

TR17-123 | 2nd August 2017
Dmitry Gavinsky, Rahul Jain, Hartmut Klauck, Srijita Kundu, Troy Lee, Miklos Santha, Swagato Sanyal, Jevgenijs Vihrovs

Quadratically Tight Relations for Randomized Query Complexity

Let $f:\{0,1\}^n \rightarrow \{0,1\}$ be a Boolean function. The certificate complexity $C(f)$ is a complexity measure that is quadratically tight for the zero-error randomized query complexity $R_0(f)$: $C(f) \leq R_0(f) \leq C(f)^2$. In this paper we study a new complexity measure that we call expectational certificate complexity $EC(f)$, which is ... more >>>

TR17-107 | 1st June 2017
Anurag Anshu, Dmitry Gavinsky, Rahul Jain, Srijita Kundu, Troy Lee, Priyanka Mukhopadhyay, Miklos Santha, Swagato Sanyal

A Composition Theorem for Randomized Query complexity

Revisions: 1

Let the randomized query complexity of a relation for error probability $\epsilon$ be denoted by $\R_\epsilon(\cdot)$. We prove that for any relation $f \subseteq \{0,1\}^n \times \mathcal{R}$ and Boolean function $g:\{0,1\}^m \rightarrow \{0,1\}$, $\R_{1/3}(f\circ g^n) = \Omega(\R_{4/9}(f)\cdot\R_{1/2-1/n^4}(g))$, where $f \circ g^n$ is the relation obtained by composing $f$ and $g$. ... more >>>

TR15-137 | 22nd August 2015
Mohammad Bavarian, Dmitry Gavinsky, Tsuyoshi Ito

On the Role of Shared Randomness in Simultaneous Communication

Two parties wish to carry out certain distributed computational tasks, and they are given access to a source of correlated random bits.
It allows the parties to act in a correlated manner, which can be quite useful.
But what happens if the shared randomness is not perfect?

In this work, ... more >>>

TR14-011 | 22nd January 2014
Dmitry Gavinsky, Pavel Pudlak

Partition Expanders

We introduce a new concept, which we call partition expanders. The basic idea is to study quantitative properties of graphs in a slightly different way than it is in the standard definition of expanders. While in the definition of expanders it is required that the number of edges between any ... more >>>

TR13-190 | 28th December 2013
Dmitry Gavinsky, Or Meir, Omri Weinstein, Avi Wigderson

Toward Better Formula Lower Bounds: An Information Complexity Approach to the KRW Composition Conjecture

Revisions: 11

One of the major open problems in complexity theory is proving super-polynomial lower bounds for circuits with logarithmic depth (i.e., $\mathbf{P}\not\subseteq\mathbf{NC}_1~$). This problem is interesting for two reasons: first, it is tightly related to understanding the power of parallel computation and of small-space computation; second, it is one of the ... more >>>

TR13-080 | 4th June 2013
Dmitry Gavinsky, Shachar Lovett

En Route to the log-rank Conjecture: New Reductions and Equivalent Formulations

We prove that several measures in communication complexity are equivalent, up to polynomial factors in the logarithm of the rank of the associated matrix: deterministic communication complexity, randomized communication complexity, information cost and zero-communication cost. This shows that in order to prove the log-rank conjecture, it suffices to show that ... more >>>

TR13-044 | 25th March 2013
Dmitry Gavinsky, Tsuyoshi Ito, Guoming Wang

Shared Randomness and Quantum Communication in the Multi-Party Model

We study shared randomness in the context of multi-party number-in-hand communication protocols in the simultaneous message passing model. We show that with three or more players, shared randomness exhibits new interesting properties that have no direct analogues in the two-party case.

First, we demonstrate a hierarchy of modes of shared ... more >>>

TR12-051 | 25th April 2012
Dmitry Gavinsky, Shachar Lovett, Michael Saks, Srikanth Srinivasan

A Tail Bound for Read-k Families of Functions

We prove a Chernoff-like large deviation bound on the sum of non-independent random variables that have the following dependence structure. The variables $Y_1,\ldots,Y_r$ are arbitrary Boolean functions of independent random variables $X_1,\ldots,X_m$, modulo a restriction that every $X_i$ influences at most $k$ of the variables $Y_1,\ldots,Y_r$.

more >>>

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

Quantum Fingerprints that Keep Secrets

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

more >>>

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

A Separation of NP and coNP in Multiparty Communication Complexity

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

more >>>

TR07-074 | 7th August 2007
Dmitry Gavinsky, Pavel Pudlak

Exponential Separation of Quantum and Classical Non-Interactive Multi-Party Communication Complexity

We give the first exponential separation between quantum and
classical multi-party
communication complexity in the (non-interactive) one-way and
simultaneous message
passing settings.
For every k, we demonstrate a relational communication problem
between k parties
that can be solved exactly by a quantum simultaneous message passing
protocol of
cost ... more >>>

TR07-058 | 9th June 2007
Dmitry Gavinsky

Classical Interaction Cannot Replace a Quantum Message

Revisions: 1

We demonstrate a two-player communication problem that can be solved in the one-way quantum model by a 0-error protocol of cost O(log n) but requires exponentially more communication in the classical interactive (two-way) model.

more >>>

TR06-086 | 25th July 2006
Dmitry Gavinsky, Julia Kempe, Ronald de Wolf

Exponential Separation of Quantum and Classical One-Way Communication Complexity for a Boolean Function

We give an exponential separation between one-way quantum and classical communication complexity for a Boolean function. Earlier such a separation was known only for a relation. A very similar result was obtained earlier but independently by Kerenidis and Raz [KR06]. Our version of the result gives an example in the ... more >>>

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