An(other) Entropy-Bounded Compressed Suffix Tree

Abstract

Suffix trees are among the most important data structures in stringology, with myriads of applications. Their main problem is space usage, which has triggered much research striving for compressed representations that are still functional. We present a novel compressed suffix tree. Compared to the existing ones, ours is the first achieving at the same time sublogarithmic complexity for the operations, and space usage which goes to zero as the entropy of the text does. Our development contains several novel ideas, such as compressing the longest common prefix information, and totally getting rid of the suffix tree topology, expressing all the suffix tree operations using range minimum queries and a new primitive called next/previous smaller value in a sequence.