Near-optimal time-space tradeoff for element distinctness

Abstract

It was conjectured by A. Borodin et al. that to solve the element distinctness problem requires TS= Omega (n/sup 2/) on a comparison-based branching program using space S and time T, which, if true, would be close to optimal since TS=O(n/sup 2/ log n) is achievable. They showed recently (1987) that TS= Omega (n/sup 3/2/(log n)/sup 1/2/). The author shows a near-optimal tradeoff TS= Omega (n/sup 2- epsilon (n)/), where epsilon (n)=O(1/(log n)/sup 1/2/).<>