Brzozowski, JanuszLi, Baiyu2017-09-292017-09-292012http://dx.doi.org/10.1007/978-3-642-31623-4_9http://hdl.handle.net/10012/12508The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-31623-4_9The syntactic complexity of a regular language is the cardinality of its syntactic semigroup. The syntactic complexity of a subclass of regular languages is the maximal syntactic complexity of languages in that subclass, taken as a function of the state complexity n of these languages. We study the syntactic complexity of three subclasses of star-free languages. We find tight upper bounds for languages accepted by monotonic, partially monotonic and “nearly monotonic” automata; all three of these classes are star-free. We conjecture that the bound for nearly monotonic languages is also a tight upper bound for star-free languages.enfinite automatonmonotonicnearly monotonicpartially monotonicstar-free languagesyntactic complexitysyntactic semigroupConference Paper