this query will match documents that contain terms accepted by a given finite-state machine. The automaton can be constructed with the Lucene.Net.Util.Automaton API. Alternatively, it can be created from a regular expression with RegexpQuery or from the standard Lucene wildcard syntax with WildcardQuery.
When the query is executed, it will create an equivalent DFA of the finite-state machine, and will enumerate the term dictionary in an intelligent way to reduce the number of comparisons. For example: the regular expression of [dl]og?
will make approximately four comparisons: do, dog, lo, and log.