Space-Efficient String Indexing for Wildcard Pattern Matching.

In this paper we describe compressed indexes that support pattern matching queries for strings with wildcards. For a constant size alphabet our data structure uses O(n log(epsilon)n) bits for any epsilon > 0 and reports all occ occurrences of a wildcard string in O(m + sigma(g).mu(n) + occ) time, where mu(n) = o(log log log n), sigma is the alphabet size, m is the number of alphabet symbols and g is the number of wildcard symbols in the query string. We also present an O(n)-bit index with O((m + sigma(g) + occ) log(epsilon)n) query time and an O(n(log log n)(2))-bit index with O((m +sigma(g) + occ) log log n) query time. These are the first non-trivial data structures for this problem that need o(n log n) bits of space.