Unrestricted State Complexity Of Binary Operations On Regular And Ideal Languages
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Date
2017-08-27
Authors
Brzozowski, Janusz
Sinnamon, Corwin
Journal Title
Journal ISSN
Volume Title
Publisher
Institut für Informatik
Abstract
We study the state complexity of binary operations on regular languages over different alphabets. It is known that if L′m and Ln are languages of state complexities m and n, respectively, and restricted to the same alphabet, the state complexity of any binary boolean operation on L′m and Ln is mn, and that of product (concatenation) is m2n − 2n−1. In contrast to this, we show that if L′m and Ln are over different alphabets, the state complexity of union and symmetric difference is (m + 1)(n + 1), that of difference is mn + m, that of intersection is mn, and that of product is m2n + 2n−1. We also study unrestricted complexity of binary operations in the classes of regular right, left, and two-sided ideals, and derive tight upper bounds. The bounds for product of the unrestricted cases (with the bounds for the restricted cases in parentheses) are as follows: right ideals m + 2n−2 + 2n−1 + 1 (m + 2n−2); left ideals mn + m + n (m + n − 1); two-sided ideals m+2n (m+n−1). The state complexities of boolean operations on all three types of ideals are the same as those of arbitrary regular languages, whereas that is not the case if the alphabets of the arguments are the same. Finally, we update the known results about most complex regular, right-ideal, left-ideal, and two-sided-ideal languages to include the unrestricted cases.
Description
This is an Accepted Manuscript of an article published by Institut für Informatik in Journal of Automata, Languages and Combinatorics on 2017-08-27, available online: http://www.jalc.de/issues/issue_22_1-3/content.html
Keywords
Boolean operation, Concatenation, Different alphabets, Left ideal, Most complex language, Product, Quotient complexity, Regular language, Right ideal, State complexity, Sream, Two-sided ideal, Unrestricted complexity