Information and Computation
Recognizable closures and submonoids of free partially commutative monoids
Theoretical Computer Science
The Book of Traces
Introduction to Automata Theory, Languages and Computability
Introduction to Automata Theory, Languages and Computability
On Regular Compatibility of Semi-Commutations
ICALP '93 Proceedings of the 20th International Colloquium on Automata, Languages and Programming
Star-Connected Flat Languages and Automata
Fundamenta Informaticae - SPECIAL ISSUE ON CONCURRENCY SPECIFICATION AND PROGRAMMING (CS&P 2005) Ruciane-Nide, Poland, 28-30 September 2005
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Up to now, star-connected rational expressions were considered only as expressions defining trace languages. In this paper we study the class of flat languages defined by this kind of rational expressions. We consider regular languages inducing recognizable trace languages and its subclasses: languages of finite ranks and star-connected languages. Main results are the following: rank of any star-connected language is finite; any star-connected language has an automaton with connected simple cycles; two pumping lemmas for star-connected languages. Moreover, we show that none of the investigated classes is closed under complement and that the class of languages of finite ranks is not closed under intersection. Finally, we briefly mention some decision problems and formulate several open questions.