All reports by Author Ryan Williams:

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TR23-186
| 28th November 2023
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Ce Jin, Ryan Williams, Nathaniel Young#### A VLSI Circuit Model Accounting For Wire Delay

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TR23-184
| 22nd November 2023
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Gabriel Bathie, Ryan Williams#### Towards Stronger Depth Lower Bounds

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TR23-171
| 15th November 2023
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Shuichi Hirahara, Rahul Ilango, Ryan Williams#### Beating Brute Force for Compression Problems

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TR23-082
| 1st June 2023
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Ryan Williams#### Self-Improvement for Circuit-Analysis Problems

Revisions: 1

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TR23-038
| 28th March 2023
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Rahul Ilango, Jiatu Li, Ryan Williams#### Indistinguishability Obfuscation, Range Avoidance, and Bounded Arithmetic

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TR21-165
| 21st November 2021
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Shyan Akmal, Lijie Chen, Ce Jin, Malvika Raj, Ryan Williams#### Improved Merlin-Arthur Protocols for Central Problems in Fine-Grained Complexity

Revisions: 1

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TR21-159
| 15th November 2021
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Lijie Chen, Ce Jin, Rahul Santhanam, Ryan Williams#### Constructive Separations and Their Consequences

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TR20-150
| 7th October 2020
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Lijie Chen, Xin Lyu, Ryan Williams#### Almost-Everywhere Circuit Lower Bounds from Non-Trivial Derandomization

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TR20-065
| 2nd May 2020
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Lijie Chen, Ce Jin, Ryan Williams#### Sharp Threshold Results for Computational Complexity

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TR19-118
| 5th September 2019
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Lijie Chen, Ce Jin, Ryan Williams#### Hardness Magnification for all Sparse NP Languages

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TR19-075
| 25th May 2019
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Lijie Chen, Dylan McKay, Cody Murray, Ryan Williams#### Relations and Equivalences Between Circuit Lower Bounds and Karp-Lipton Theorems

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TR17-188
| 22nd December 2017
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Cody Murray, Ryan Williams#### Circuit Lower Bounds for Nondeterministic Quasi-Polytime: An Easy Witness Lemma for NP and NQP

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TR16-002
| 18th January 2016
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Ryan Williams#### Strong ETH Breaks With Merlin and Arthur: Short Non-Interactive Proofs of Batch Evaluation

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TR15-188
| 24th November 2015
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Daniel Kane, Ryan Williams#### Super-Linear Gate and Super-Quadratic Wire Lower Bounds for Depth-Two and Depth-Three Threshold Circuits

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TR14-164
| 30th November 2014
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Cody Murray, Ryan Williams#### On the (Non) NP-Hardness of Computing Circuit Complexity

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TR13-108
| 9th August 2013
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Rahul Santhanam, Ryan Williams#### New Algorithms for QBF Satisfiability and Implications for Circuit Complexity

Revisions: 1

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TR12-107
| 30th August 2012
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Brendan Juba, Ryan Williams#### Massive Online Teaching to Bounded Learners

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TR12-059
| 14th May 2012
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Rahul Santhanam, Ryan Williams#### Uniform Circuits, Lower Bounds, and QBF Algorithms

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TR11-031
| 8th March 2011
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Sam Buss, Ryan Williams#### Limits on Alternation-Trading Proofs for Time-Space Lower Bounds

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TR08-076
| 17th June 2008
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Ryan Williams#### Non-Linear Time Lower Bound for (Succinct) Quantified Boolean Formulas

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TR07-036
| 6th April 2007
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Ryan Williams#### Time-Space Tradeoffs for Counting NP Solutions Modulo Integers

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TR04-032
| 5th February 2004
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Ryan Williams#### A new algorithm for optimal constraint satisfaction and its implications

Ce Jin, Ryan Williams, Nathaniel Young

Given the need for ever higher performance, and the failure of CPUs to keep providing single-threaded performance gains, engineers are increasingly turning to highly-parallel custom VLSI chips to implement expensive computations. In VLSI design, the gates and wires of a logical circuit are placed on a 2-dimensional chip with a ... more >>>

Gabriel Bathie, Ryan Williams

A fundamental problem in circuit complexity is to find explicit functions that require large depth to compute. When considering the natural DeMorgan basis of $\{\text{OR},\text{AND}\}$, where negations incur no cost, the best known depth lower bounds for an explicit function in NP have the form $(3-o(1))\log_2 n$, established by H{\aa}stad ... more >>>

Shuichi Hirahara, Rahul Ilango, Ryan Williams

A compression problem is defined with respect to an efficient encoding function $f$; given a string $x$, our task is to find the shortest $y$ such that $f(y) = x$. The obvious brute-force algorithm for solving this compression task on $n$-bit strings runs in time $O(2^{\ell} \cdot t(n))$, where $\ell$ ... more >>>

Ryan Williams

Many results in fine-grained complexity reveal intriguing consequences from solving various SAT problems even slightly faster than exhaustive search. We prove a ``self-improving'' (or ``bootstrapping'') theorem for Circuit-SAT, $\#$Circuit-SAT, and its fully-quantified version: solving one of these problems faster for ``large'' circuit sizes implies a significant speed-up for ``smaller'' circuit ... more >>>

Rahul Ilango, Jiatu Li, Ryan Williams

The range avoidance problem (denoted by Avoid) asks to find a string outside of the range of a given circuit $C:\{0,1\}^n\to\{0,1\}^m$, where $m>n$. Although at least half of the strings of length $m$ are correct answers, it is not clear how to deterministically find one. Recent results of Korten (FOCS'21) ... more >>>

Shyan Akmal, Lijie Chen, Ce Jin, Malvika Raj, Ryan Williams

In a Merlin-Arthur proof system, the proof verifier (Arthur) accepts valid proofs (from Merlin) with probability $1$, and rejects invalid proofs with probability arbitrarily close to $1$. The running time of such a system is defined to be the length of Merlin's proof plus the running time of Arthur. We ... more >>>

Lijie Chen, Ce Jin, Rahul Santhanam, Ryan Williams

For a complexity class $C$ and language $L$, a constructive separation of $L \notin C$ gives an efficient algorithm (also called a refuter) to find counterexamples (bad inputs) for every $C$-algorithm attempting to decide $L$. We study the questions: Which lower bounds can be made constructive? What are the consequences ... more >>>

Lijie Chen, Xin Lyu, Ryan Williams

In certain complexity-theoretic settings, it is notoriously difficult to prove complexity separations which hold almost everywhere, i.e., for all but finitely many input lengths. For example, a classical open question is whether $\mathrm{NEXP} \subset \mathrm{i.o.-}\mathrm{NP}$; that is, it is open whether nondeterministic exponential time computations can be simulated on infinitely ... more >>>

Lijie Chen, Ce Jin, Ryan Williams

We establish several ``sharp threshold'' results for computational complexity. For certain tasks, we can prove a resource lower bound of $n^c$ for $c \geq 1$ (or obtain an efficient circuit-analysis algorithm for $n^c$ size), there is strong intuition that a similar result can be proved for larger functions of $n$, ... more >>>

Lijie Chen, Ce Jin, Ryan Williams

In the Minimum Circuit Size Problem (MCSP[s(m)]), we ask if there is a circuit of size s(m) computing a given truth-table of length n = 2^m. Recently, a surprising phenomenon termed as hardness magnification by [Oliveira and Santhanam, FOCS 2018] was discovered for MCSP[s(m)] and the related problem MKtP of ... more >>>

Lijie Chen, Dylan McKay, Cody Murray, Ryan Williams

Relations and Equivalences Between Circuit Lower Bounds and Karp-Lipton Theorems

A frontier open problem in circuit complexity is to prove P^NP is not in SIZE[n^k] for all k; this is a necessary intermediate step towards NP is not in P/poly. Previously, for several classes containing P^NP, including NP^NP, ZPP^NP, and ... more >>>

Cody Murray, Ryan Williams

We prove that if every problem in $NP$ has $n^k$-size circuits for a fixed constant $k$, then for every $NP$-verifier and every yes-instance $x$ of length $n$ for that verifier, the verifier's search space has an $n^{O(k^3)}$-size witness circuit: a witness for $x$ that can be encoded with a circuit ... more >>>

Ryan Williams

We present an efficient proof system for Multipoint Arithmetic Circuit Evaluation: for every arithmetic circuit $C(x_1,\ldots,x_n)$ of size $s$ and degree $d$ over a field ${\mathbb F}$, and any inputs $a_1,\ldots,a_K \in {\mathbb F}^n$,

$\bullet$ the Prover sends the Verifier the values $C(a_1), \ldots, C(a_K) \in {\mathbb F}$ and ...
more >>>

Daniel Kane, Ryan Williams

In order to formally understand the power of neural computing, we first need to crack the frontier of threshold circuits with two and three layers, a regime that has been surprisingly intractable to analyze. We prove the first super-linear gate lower bounds and the first super-quadratic wire lower bounds for ... more >>>

Cody Murray, Ryan Williams

The Minimum Circuit Size Problem (MCSP) is: given the truth table of a Boolean function $f$ and a size parameter $k$, is the circuit complexity of $f$ at most $k$? This is the definitive problem of circuit synthesis, and it has been studied since the 1950s. Unlike many problems of ... more >>>

Rahul Santhanam, Ryan Williams

We revisit the complexity of the satisfiability problem for quantified Boolean formulas. We show that satisfiability

of quantified CNFs of size $\poly(n)$ on $n$ variables with $O(1)$

quantifier blocks can be solved in time $2^{n-n^{\Omega(1)}}$ by zero-error

randomized algorithms. This is the first known improvement over brute force search in ...
more >>>

Brendan Juba, Ryan Williams

We consider a model of teaching in which the learners are consistent and have bounded state, but are otherwise arbitrary. The teacher is non-interactive and ``massively open'': the teacher broadcasts a sequence of examples of an arbitrary target concept, intended for every possible on-line learning algorithm to learn from. We ... more >>>

Rahul Santhanam, Ryan Williams

We explore the relationships between circuit complexity, the complexity of generating circuits, and circuit-analysis algorithms. Our results can be roughly divided into three parts:

1. Lower Bounds Against Medium-Uniform Circuits. Informally, a circuit class is ``medium uniform'' if it can be generated by an algorithmic process that is somewhat complex ... more >>>

Sam Buss, Ryan Williams

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 >>>

Ryan Williams

We prove a model-independent non-linear time lower bound for a slight generalization of the quantified Boolean formula problem (QBF). In particular, we give a reduction from arbitrary languages in alternating time t(n) to QBFs describable in O(t(n)) bits by a reasonable (polynomially) succinct encoding. The reduction works for many reasonable ... more >>>

Ryan Williams

We prove the first time-space tradeoffs for counting the number of solutions to an NP problem modulo small integers, and also improve upon the known time-space tradeoffs for Sat. Let m be a positive integer, and define MODm-Sat to be the problem of determining if a given Boolean formula has ... more >>>

Ryan Williams

We present a novel method for exactly solving (in fact, counting solutions to) general constraint satisfaction optimization with at most two variables per constraint (e.g. MAX-2-CSP and MIN-2-CSP), which gives the first exponential improvement over the trivial algorithm; more precisely, it is a constant factor improvement in the base of ... more >>>