This paper is motivated by the results in [M. Ito, Algebraic structures of automata, Theoretical Computer Science 428 (2012) 164-168.]. Structures and the number of subautomata of a finite automaton are investigated. It is shown that the set of all subautomata of a finite automaton A is upper semilattice. We give conditions which allow us to determine whether for a finite upper semilattice (L;≤) there exists an automaton A such that the set of all subautomata of A under set inclusion is isomorphic to (L;≤). Examples illustrating the results are presented.
Atani, S. E., Bazari, M. S. S. (2020). Lattice structures of automata. Communications Faculty of Sciences University of Ankara Series A1 Mathematics and Statistics, Volume: 69 Issue: 2. https://doi.org/10.31801/cfsuasmas.675691