We provide several advances to the understanding of the class of quantum Merlin--Arthur (QMA) proof systems, the quantum analogue of NP. Our central contribution is proving a longstanding conjecture that the consistency of local density matrices (CLDM) ...

Yao's circuit garbling scheme is one of the basic building blocks of cryptographic protocol design. Originally designed to enable two-message, two-party secure computation, the scheme has been extended in many ways and has innumerable applications. ...

This paper considers a special class of nonlocal games $(G,\psi)$, where $G$ is a two-player one-round game, and $\psi$ is a bipartite state independent of $G$. In the game $(G,\psi)$, the players are allowed to share arbitrarily many copies of $\psi$. The ...

In this paper, we prove the first fixed-depth size-hierarchy theorem for uniform ${\mathrm{AC}}^0[\oplus]$. In particular, we show that for any fixed $d$ and integer parameter $k$, the class ${\mathcal{{C}}}_{d,k}$ of functions that have uniform ${\mathrm{AC}...

We show that for constraint satisfaction problems (CSPs), weakly exponential size linear programming relaxations are as powerful as the explicit linear program described by $n^{\Omega(1)}$-rounds of the Sherali--Adams linear programming hierarchy. ...

In a recent breakthrough, [C. Murray and R. R. Williams, STOC 2018, ACM, New York, 2018, pp. 890--901] proved that ${NQP} = {NTIME}[n^{{polylog}(n)}]$ cannot be computed by polynomial-size ${ACC}^0$ circuits (constant-depth circuits consisting of ${AND}$/...

This note indicates an error in the proof of Theorem 3.1 in [T. Vidick, SIAM J. Comput., 45 (2016), pp. 1007--1063]. Due to an induction step in the soundness analysis not being carried out correctly, the analysis fails to prove the claimed result. The ...

We initiate the study of the communication complexity of fair division with indivisible goods. We focus on some of the most well studied fairness notions (envy-freeness, proportionality, and approximations thereof) and valuation classes (submodular, ...

The tractability conjecture for finite domain constraint satisfaction problems (CSPs) stated that such CSPs are solvable in polynomial time whenever there is no natural reduction, in some precise technical sense, from the 3-SAT problem; otherwise, they ...

Non-malleable commitments are a fundamental cryptographic tool for preventing (concurrent) man-in-the-middle attacks. Since their invention by Dolev, Dwork, and Naor in 1991, their round-complexity has been extensively studied, leading up to constant-round ...

For any $n$-bit boolean function $f$, we show that the randomized communication complexity of the composed function $f\circ g^n$, where $g$ is an index gadget, is characterized by the randomized decision tree complexity of $f$. In particular, this means ...

It is shown that the parity game can be solved in quasi-polynomial time. The parameterized parity game---with $n$ nodes and $m$ distinct values (a.k.a. colors or priorities)---is proven to be in the class of fixed parameter tractable problems when ...

This paper proves the first superlogarithmic lower bounds on the cell probe complexity of dynamic Boolean (also known as decision) data structure problems, a long-standing milestone in data structure lower bounds. We introduce a new method for proving ...

In this work we provide a traitor tracing construction with ciphertexts that grow polynomially in $\log(n)$, where $n$ is the number of users, and prove it secure under the learning with errors (LWE) assumption. This is the first traitor tracing scheme ...

Nisan [Combinatorica, 12 (1992), pp. 449--461] 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 ...

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 ...

Surprising and beautiful depth reduction results show that sufficiently strong lower bounds for bounded-depth arithmetic circuits imply superpolynomial lower bounds for general arithmetic circuits. Motivated by this, in the last few years, there has been ...

We study the computational complexity of short sentences in Presburger arithmetic (Short-PA). Here by “short” we mean sentences with a bounded number of variables, quantifiers, inequalities, and Boolean operations; the input consists only of the integer ...

We show that every circuit with ${AND},{OR},{NOT}$, and ${MOD}_m$ gates, $m\in\mathbb{Z}^+$, of polynomial size and depth $d$ can be reduced to a depth-2, ${SYM}\circ{AND}$, circuit of size $2^{(\log n)^{O(d)}}$. This is an exponential size improvement ...

For $n\geq 3$, let $(H_n, E)$ denote the $n$th Henson graph, i.e., the unique countable homogeneous graph with exactly those finite graphs as induced subgraphs that do not embed the complete graph on $n$ vertices. We show that for all structures $\Gamma$ ...