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Electronic Colloquium on Computational Complexity

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All reports by Author Dean Doron:

TR21-020 | 15th February 2021
Gil Cohen, Dean Doron, Oren Renard, Ori Sberlo, Amnon Ta-Shma

Error Reduction For Weighted PRGs Against Read Once Branching Programs

Weighted pseudorandom generators (WPRGs), introduced by Braverman, Cohen and Garg [BCG20], is a generalization of pseudorandom generators (PRGs) in which arbitrary real weights are considered rather than a probability mass. Braverman et al. constructed WPRGs against read once branching programs (ROBPs) with near-optimal dependence on the error parameter. Chattopadhyay and ... more >>>

TR21-018 | 20th February 2021
Dean Doron, Raghu Meka, Omer Reingold, Avishay Tal, Salil Vadhan

Monotone Branching Programs: Pseudorandomness and Circuit Complexity

We study monotone branching programs, wherein the states at each time step can be ordered so that edges with the same labels never cross each other. Equivalently, for each fixed input, the transition functions are a monotone function of the state.

We prove that constant-width monotone branching programs of ... more >>>

TR20-162 | 7th November 2020
Dean Doron, Mary Wootters

High-Probability List-Recovery, and Applications to Heavy Hitters

Revisions: 1

An error correcting code $\mathcal{C} \colon \Sigma^k \to \Sigma^n$ is list-recoverable from input list size $\ell$ if for any sets $\mathcal{L}_1, \ldots, \mathcal{L}_n \subseteq \Sigma$ of size at most $\ell$, one can efficiently recover the list $\mathcal{L} = \{ x \in \Sigma^k : \forall j \in [n], \mathcal{C}(x)_j \in \mathcal{L}_j ... more >>>

TR20-161 | 5th November 2020
Gil Cohen, Dean Doron, Shahar Samocha

Seed Protecting Extractors

We introduce a new type of seeded extractors we dub seed protecting extractors. Informally, a seeded extractor is seed protecting against a class of functions $C$, mappings seeds to seeds, if the seed $Y$ remains close to uniform even after observing the output $\mathrm{Ext}(X,A(Y))$ for every choice of $A \in ... more >>>

TR20-026 | 25th February 2020
Dean Doron, Jack Murtagh, Salil Vadhan, David Zuckerman

Spectral Sparsification via Bounded-Independence Sampling

Revisions: 1

We give a deterministic, nearly logarithmic-space algorithm for mild spectral sparsification of undirected graphs. Given a weighted, undirected graph $G$ on $n$ vertices described by a binary string of length $N$, an integer $k\leq \log n$ and an error parameter $\varepsilon > 0$, our algorithm runs in space $\tilde{O}(k\log (N\cdot ... more >>>

TR19-149 | 4th November 2019
Dean Doron, Pooya Hatami, William Hoza

Log-Seed Pseudorandom Generators via Iterated Restrictions

There are only a few known general approaches for constructing explicit pseudorandom generators (PRGs). The ``iterated restrictions'' approach, pioneered by Ajtai and Wigderson [AW89], has provided PRGs with seed length $\mathrm{polylog} n$ or even $\tilde{O}(\log n)$ for several restricted models of computation. Can this approach ever achieve the optimal seed ... more >>>

TR19-119 | 9th September 2019
Dean Doron, Amnon Ta-Shma, Roei Tell

On Hitting-Set Generators for Polynomials that Vanish Rarely

Revisions: 1

We study the following question: Is it easier to construct a hitting-set generator for polynomials $p:\mathbb{F}^n\rightarrow\mathbb{F}$ of degree $d$ if we are guaranteed that the polynomial vanishes on at most an $\epsilon>0$ fraction of its inputs? We will specifically be interested in tiny values of $\epsilon\ll d/|\mathbb{F}|$. This question was ... more >>>

TR19-099 | 29th July 2019
Dean Doron, Dana Moshkovitz, Justin Oh, David Zuckerman

Nearly Optimal Pseudorandomness From Hardness

Revisions: 3

Existing proofs that deduce $\mathbf{BPP}=\mathbf{P}$ from circuit lower bounds convert randomized algorithms into deterministic algorithms with a large polynomial slowdown. We convert randomized algorithms into deterministic ones with little slowdown. Specifically, assuming exponential lower bounds against nondeterministic circuits, we convert any randomized algorithm over inputs of length $n$ running in ... more >>>

TR18-183 | 5th November 2018
Dean Doron, Pooya Hatami, William Hoza

Near-Optimal Pseudorandom Generators for Constant-Depth Read-Once Formulas

Revisions: 2

We give an explicit pseudorandom generator (PRG) for constant-depth read-once formulas over the basis $\{\wedge, \vee, \neg\}$ with unbounded fan-in. The seed length of our PRG is $\widetilde{O}(\log(n/\varepsilon))$. Previously, PRGs with near-optimal seed length were known only for the depth-2 case (Gopalan et al. FOCS '12). For a constant depth ... more >>>

TR18-066 | 8th April 2018
Avraham Ben-Aroya, Gil Cohen, Dean Doron, Amnon Ta-Shma

Two-Source Condensers with Low Error and Small Entropy Gap via Entropy-Resilient Functions

In their seminal work, Chattopadhyay and Zuckerman (STOC'16) constructed a two-source extractor with error $\varepsilon$ for $n$-bit sources having min-entropy $poly\log(n/\varepsilon)$. Unfortunately, the construction running-time is $poly(n/\varepsilon)$, which means that with polynomial-time constructions, only polynomially-large errors are possible. Our main result is a $poly(n,\log(1/\varepsilon))$-time computable two-source condenser. For any $k ... more >>>

TR18-065 | 8th April 2018
Avraham Ben-Aroya, Dean Doron, Amnon Ta-Shma

Near-Optimal Strong Dispersers, Erasure List-Decodable Codes and Friends

Revisions: 1

A code $\mathcal{C}$ is $(1-\tau,L)$ erasure list-decodable if for every codeword $w$, after erasing any $1-\tau$ fraction of the symbols of $w$,
the remaining $\tau$-fraction of its symbols have at most $L$ possible completions into codewords of $\mathcal{C}$.
Non-explicitly, there exist binary $(1-\tau,L)$ erasure list-decodable codes having rate $O(\tau)$ and ... more >>>

TR17-036 | 22nd February 2017
Dean Doron, Francois Le Gall, Amnon Ta-Shma

Probabilistic logarithmic-space algorithms for Laplacian solvers

A recent series of breakthroughs initiated by Spielman and Teng culminated in the construction of nearly linear time Laplacian solvers, approximating the solution of a linear system $L x=b$, where $L$ is the normalized Laplacian of an undirected graph. In this paper we study the space complexity of the problem.
more >>>

TR17-027 | 16th February 2017
Avraham Ben-Aroya, Eshan Chattopadhyay, Dean Doron, Xin Li, Amnon Ta-Shma

A reduction from efficient non-malleable extractors to low-error two-source extractors with arbitrary constant rate

Revisions: 1

We show a reduction from the existence of explicit t-non-malleable
extractors with a small seed length, to the construction of explicit
two-source extractors with small error for sources with arbitrarily
small constant rate. Previously, such a reduction was known either
when one source had entropy rate above half [Raz05] or ... more >>>

TR16-120 | 1st August 2016
Dean Doron, Amir Sarid, Amnon Ta-Shma

On approximating the eigenvalues of stochastic matrices in probabilistic logspace

Revisions: 1

Approximating the eigenvalues of a Hermitian operator can be solved
by a quantum logspace algorithm. We introduce the problem of
approximating the eigenvalues of a given matrix in the context of
classical space-bounded computation. We show that:

- Approximating the second eigenvalue of stochastic operators (in a
certain range of ... more >>>

TR16-106 | 15th July 2016
Avraham Ben-Aroya, Dean Doron, Amnon Ta-Shma

Low-error two-source extractors for polynomial min-entropy

Revisions: 1

We construct explicit two-source extractors for $n$ bit sources,
requiring $n^\alpha$ min-entropy and having error $2^{-n^\beta}$,
for some constants $0 < \alpha,\beta < 1$. Previously, constructions
for exponentially small error required either min-entropy
$0.49n$ \cite{Bou05} or three sources \cite{Li15}. The construction
combines somewhere-random condensers based on the Incidence
Theorem \cite{Zuc06,Li11}, ... more >>>

TR16-088 | 1st June 2016
Avraham Ben-Aroya, Dean Doron, Amnon Ta-Shma

Explicit two-source extractors for near-logarithmic min-entropy

We explicitly construct extractors for two independent $n$-bit sources of $(\log n)^{1+o(1)}$ min-entropy. Previous constructions required either $\mathrm{polylog}(n)$ min-entropy \cite{CZ15,Meka15} or five sources \cite{Cohen16}.

Our result extends the breakthrough result of Chattopadhyay and Zuckerman \cite{CZ15} and uses the non-malleable extractor of Cohen \cite{Cohen16}. The main new ingredient in our construction ... more >>>

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