  We study the pattern matching automaton introduced in (A unifying framework
for seed sensitivity and its application to subset seeds) for the purpose of
seed-based similarity search. We show that our definition provides a compact
automaton, much smaller than the one obtained by applying the Aho-Corasick
construction. We study properties of this automaton and present an efficient
implementation of the automaton construction. We also present some experimental
results and show that this automaton can be successfully applied to more
general situations.
