Nondeterministic Automata and JSL-dfas

Abstract

We introduce the category of dependency automata. A dependency automaton consists of two nondeterministic finite automata, with a relation between their states satisfying conditions. This category is equivalent to deterministic finite automata interpreted in join-semilattices i.e. JSL-dfas. The canonical dependency automaton accepting $L$ amounts to the state-minimal dfas for $L$ and $rev(L)$ connected by the `dependency relation'. We describe many canonical JSL-dfas as dependency automata and also explain/extend Brzozowski's algorithm. Call an nfa `subatomic' if its individual states accept a language in the closure of $\{L\}$ under left/right quotients and set-theoretic boolean operations. We prove an nfa $N$ is subatomic iff $rsc(rev(N))$'s transition monoid is syntactic.