A Searchable Compressed Edit-Sensitive Parsing

A searchable data structure for the edit-sensitive parsing (ESP) is proposed. Given a string S, its ESP tree is equivalent to a context-free grammar G generating just S, which is represented by a DAG. Using the succinct data structures for trees and permutations, G is decomposed to two LOUDS bit strings and single array in (1+ε)n log n+ 4n+o(n) bits for any 0 < ε < 1 and the number n of variables in G. The time to count occurrences of P in S is in O( 1 ε (m log n+occc(logm log u)), whereas m = |P |, u = |S|, and occc is the number of occurrences of a maximal common subtree in ESPs of P and S. The efficiency of the proposed index is evaluated by the experiments conducted on several benchmarks complying with the other compressed indexes.