Title
ANTICONCENTRATION AND THE EXACT GAP-HAMMING PROBLEM
Abstract
We prove anticoncentration bounds for the inner product of two independent random vectors and use these bounds to prove lower bounds in communication complexity. We show that if A, B are subsets of the cube {+/- 1}(n) with vertical bar A vertical bar .vertical bar B vertical bar 2(1.01n), and X is an element of A and Y is an element of B are sampled independently and uniformly, then the inner product < X, Y > takes on any fixed value with probability at most O(1/root n). In fact, we prove the following stronger "smoothness" "statement: max(k) vertical bar Pr[< X, Y > = k] Pr[< X, Y >= k + 4] <= O(1/n). We use these results to prove that the exact gap-hamming problem requires linear communication, resolving an open problem in communication complexity. We also conclude anticoncentration for structured distributions with low entropy. If x is an element of Z(n) has no zero coordinates, and B subset of{+/- 1}(n) corresponds to a subspace of F-2(n) of dimension 0.51n, then max(k) Pr[< x, Y > = k <= O(root ln(n)/n).
Year
DOI
Venue
2022
10.1137/21M1435288
SIAM JOURNAL ON DISCRETE MATHEMATICS
Keywords
DocType
Volume
communication complexity, anticoncentration, probability
Journal
36
Issue
ISSN
Citations 
2
0895-4801
0
PageRank 
References 
Authors
0.34
0
2
Name
Order
Citations
PageRank
Anup Rao158132.80
Amir Yehudayoff200.34