Atani, Shahabaddin EbrahimiSedghi Shanbeh Bazari, Maryam2021-11-232021-11-232020-12-31https://doi.org/10.31801/cfsuasmas.675691http://hdl.handle.net/20.500.12575/76225This 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.enAutomatonSubautomatonUpper semilatticeArticle692113311452618-6470