Converting Suffix Trees into Factor/Suffix Oracles
Résumé
The factor/suffix oracle is an automaton introduced by Allauzen, Crochemore and Raffinot. It is built for a given sequence s on an alphabet , and it weakly recognizes all the factors (the suffixes, respectively) of s : that is, it certainly recognizes all the factors (suffixes, respectively) of s, but possibly recognizes words that are not factors (not suffixes, respectively) of s. However, it can still be suitably used to solve pattern matching and compression problems. The main advantage of the factor/suffix oracle with respect to other indexes is its size: it has a minimum number of states and a very small (although not minimum) number of transitions. In this paper, we show that the factor/suffix oracle can be obtained from another indexing structure, the suffix tree, by a linear algorithm. This improves the quadratic complexity previously known for the same task.
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