All that distinguishes the de?nition of the class of Regular languages from that of the class of Star-Free languages is that the former is closed under Kleene closure while the latter is closed only under complement. Since the Star-Free languages are exactly the LTO languages which are a subclass of the Recognizable languages and the class of Recognizable languages is closed under union, concatenation and Kleene closure, it follows that every Regular language is Recognizable.