Time-Space Lower Bounds for the Polynomial-Time Hierarchy on Randomized Machines
We establish the first polynomial-strength time-space lower bounds for problems in the linear-time hierarchy on randomized machines with two-sided error. We show that for any integer $\ell > 1$ and constant $c < \ell$, there exists a positive constant $...
Infinitely-Often Autoreducible Sets
A set $A$ is autoreducible if one can compute, for all $x$, the value $A(x)$ by querying $A$ only at places $y \neq x$. Furthermore, $A$ is infinitely-often autoreducible if, for infinitely many $x$, the value $A(x)$ can be computed by querying $A$ only ...
An Extension of the Lova´sz Local Lemma, and its Applications to Integer Programming
The Lova´sz local lemma due to Erdo˝s and Lova´sz (Infinite and Finite Sets, Colloq. Math. Soc. J. Bolyai 11, 1975, pp. 609-627) is a powerful tool in proving the existence of rare events. We present an extension of this lemma, which works well when the ...
Approximating Longest Cycles in Graphs with Bounded Degrees
Jackson and Wormald conjecture that if $G$ is a 3-connected $n$-vertex graph with maximum degree $d\ge 4$, then $G$ has a cycle of length $\Omega(n^{\log_{d-1}2})$. We show that this conjecture holds when $d-1$ is replaced by $\max\{64,4d+1\}$. Our ...
Fairness Measures for Resource Allocation
In many optimization problems, one seeks to allocate a limited set of resources to a set of individuals with demands. Thus, such allocations can naturally be viewed as vectors, with one coordinate representing each individual. Motivated by work in ...
Dynamic Subgraph Connectivity with Geometric Applications
Inspired by dynamic connectivity applications in computational geometry, we consider a problem we call dynamic subgraph connectivity: design a data structure for an undirected graph $G=(V,E)$ and a subset of vertices $S \subseteq V$ to support ...
On the Number of Crossing-Free Matchings, Cycles, and Partitions
We show that a set of $n$ points in the plane has at most $O(10.05^n)$ perfect matchings with crossing-free straight-line embedding. The expected number of perfect crossing-free matchings of a set of $n$ points drawn independently and identically ...
Counting and Enumerating Pointed Pseudotriangulations with the Greedy Flip Algorithm
We present an algorithm to enumerate the pointed pseudotriangulations of a given point set, based on the greedy flip algorithm of Pocchiola and Vegter [Discrete Comput. Geom. 16 (1996), pp. 419-453]. Our two independent implementations agree and allow ...
Random $k$-SAT: Two Moments Suffice to Cross a Sharp Threshold
Many NP-complete constraint satisfaction problems appear to undergo a “phase transition” from solubility to insolubility when the constraint density passes through a critical threshold. In all such cases it is easy to derive upper bounds on the location ...
Quantum Algorithms for Some Hidden Shift Problems
Almost all of the most successful quantum algorithms discovered to date exploit the ability of the Fourier transform to recover subgroup structures of functions, especially periodicity. The fact that Fourier transforms can also be used to capture shift ...
Testing Polynomials over General Fields
In this work we fill the knowledge gap concerning testing polynomials over finite fields. As previous works show, when the cardinality of the field, $q$, is sufficiently larger than the degree bound, $d$, then the number of queries sufficient for ...
Exponential Determinization for Ω-Automata with a Strong Fairness Acceptance Condition
In [S. Safra, Proceedings of the 29th IEEE Symposium on Foundations of Computer Science, 1988, pp. 319-327] an exponential determinization procedure for Buchi automata was shown, yielding tight bounds for decision procedures of some logics (see [A. E. ...
Computing Maximally Separated Sets in the Plane
Let $S$ be a set of $n$ points in $\reals^2$. Given an integer $1 \le k \le n$, we wish to find a maximally separated subset $I \subseteq S$ of size $k$; this is a subset for which the minimum among the ${k\choose 2}$ pairwise distances between its ...
A Probabilistic Approach to the Dichotomy Problem
Let ${\mathcal R}(n,k)$ denote the random $k$-ary relation defined on the set $[n]=\{1,2,\dots,n\}$. We show that the probability that $([n], {\mathcal R}(n,k))$ is projective tends to one, as either $n$ or $k$ tends to infinity. This result implies ...