Lempel-Ziv parsing and sublinear-size index structures for string matching

String matching over a long text can be signiicantly speeded up with an index structure formed by preprocessing the text. For very long texts, the size of such an index can be a problem. This paper presents the rst sublinear-size index structure. The new structure is based on Lempel-Ziv parsing of the text and has size linear in N, the size of the Lempel-Ziv parse. For a text of length n, N = O(n= log n) and can be still smaller if the text is compressible. With the new index structure, all occurrences of a pattern string of length m can be found in time O(m 2 + (m + L) log N + p Nm log m), where L is the number of occurrences found.