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Complexity of atoms, combinatorially. (English) Zbl 1352.68130

Summary: Atoms of a (regular) language \(L\) were introduced by J. Brzozowski and H. Tamm in [Lect. Notes Comput. Sci. 6795, 105–116 (2011; Zbl 1221.68117)] as intersections of complemented and uncomplemented quotients of \(L\). They derived tight upper bounds on the complexity of atoms in [J. Brzozowski and H. Tamm, ibid. 7410, 50–61 (2012; Zbl 1352.68127)]. In [“Maximally atomic languages”, in: Proceedings of the 14th international conference on automata and formal languages, AFL 2014, Szeged, Hungary, May 27–29, 2014, in: Electron. Proc. Theor. Comput. Sci. 151, 151–161 (2014)], J. Brzozowski and G. Davies characterized the regular languages meeting these bounds. To achieve these results, they used the so-called “átomaton” of a language, introduced by Brzozowski and Tamm in [Zbl 1221.68117]. In this note we give an alternative proof of their characterization, via a purely combinatorial approach.

MSC:

68Q45 Formal languages and automata

References:

[1] André, Jorge M., Semigroups that contain all singular transformations, Semigroup Forum, 68, 2, 304-307 (2004) · Zbl 1069.20058
[2] Brzozowski, Janusz; Davies, Sylvie, Quotient complexities of atoms in regular ideal languages, Acta Cybern., 22, 2, 293-311 (2015) · Zbl 1349.68122
[3] Brzozowski, Janusz; Szykuła, Marek, Complexity of suffix-free regular languages, (Kosowski, Adrian; Walukiewicz, Igor, Fundamentals of Computation Theory. Fundamentals of Computation Theory, Lecture Notes in Computer Science, vol. 9210 (2015), Springer International Publishing), 146-159 · Zbl 1434.68239
[4] Brzozowski, Janusz A.; Davies, Gareth, Maximal syntactic complexity of regular languages implies maximal quotient complexities of atoms (2012), CoRR
[5] Brzozowski, Janusz A.; Davies, Gareth, Maximally atomic languages, (Ésik, Zoltán; Fülöp, Zoltán, Proceedings 14th International Conference on Automata and Formal Languages. Proceedings 14th International Conference on Automata and Formal Languages, AFL 2014, Szeged, Hungary, May 27-29, 2014. Proceedings 14th International Conference on Automata and Formal Languages. Proceedings 14th International Conference on Automata and Formal Languages, AFL 2014, Szeged, Hungary, May 27-29, 2014, EPTCS, vol. 151 (2014)), 151-161 · Zbl 1464.68156
[6] Brzozowski, Janusz A.; Tamm, Hellis, Theory of átomata, (Mauri, Giancarlo; Leporati, Alberto, Developments in Language Theory. Developments in Language Theory, Lecture Notes in Computer Science, vol. 6795 (2011), Springer: Springer Berlin, Heidelberg), 105-116 · Zbl 1221.68117
[7] Brzozowski, Janusz A.; Tamm, Hellis, Quotient complexities of atoms of regular languages, (Yen, Hsu-Chun; Ibarra, Oscar H., Developments in Language Theory. Developments in Language Theory, Lecture Notes in Computer Science, vol. 7410 (2012), Springer), 50-61 · Zbl 1352.68127
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