Algorithms for Converting Finite Automata Corresponding to Infinite Iterative Trees

• Main Authors: Mikhail Abramyan, Boris Melnikov
• Format: Article
• Language: Russian
• Published: The Fund for Promotion of Internet media, IT education, human development «League Internet Media» 2021-04-01
• Series: Современные информационные технологии и IT-образование
• Subjects: algorithms; formal languages; iterations of languages; binary relations; infinite trees
• Online Access: http://sitito.cs.msu.ru/index.php/SITITO/article/view/728

In this paper, we work with some different variants of finite automata, each of which corresponds to an infinite iterative tree constructed for some given morphism. At the same time, each of the automata constructed for a given morphism describes the main properties of this morphism. Besides, in each case (i.e., for each variant of the automaton), the following “inverse problem” also arises: to describe the morphism (or simply specify a pair of languages) for which such a given automaton is obtained. We present a computer program for constructing one such automaton, so-called PRI automaton. After that, we consider a detailed example of a PRI automaton for a pair of different languages. Continuing to consider this example, we use the last automaton to perform usual transformations described and repeatedly applied in our previous publications, i.e., the determination and canonization of the mirror automaton for possible application of the results obtained in the algorithm for minimizing nondeterministic automata. In the considered situation, such a minimal automaton is another automaton constructed on the basis of a given morphism tree, a nondeterministic automaton, the so-called NSPRI# automaton, and we also show the equality of these automata (which implies the equivalence of PRI and NSPRI#) in the paper by an example. Based on the NSPRI# automaton, a non-deterministic NSPRI automaton is constructed using a trivial (but non-equivalent) transformation; a detailed study of this automaton is expected in future publications. Examples of PRI and NSPRI# automata for pairs of matching languages are also of interest, we also give one such example in this paper.