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A Partial Deterministic Automaton for Approximate String Matching

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Gonzalo Navarro

One of the simplest approaches to approximate string matching is to consider
the associated non-deterministic finite automaton and make it deterministic.
Besides automaton generation, the search time is *O (n)* in the worst case, where
*n* is the text size.
This solution is mentioned in the classical literature but has not been further
pursued, due to the large number of automaton states that may be generated.
We study the idea of generating the deterministic automaton on the fly.
That is, we only generate the states that are actually reached when the text is
traversed. We show that this limits drastically the number of states actually
generated. Moreover, the algorithm is competitive, being the fastest one
for intermediate error ratios and pattern lengths.