Is there algorithm to incrementally update (minimal) DFA? Namely, having relatively large minimized DFA I want to update it incrementally using union and sudtraction with other (relatively small, minimal) DFAs? Updates should preserve determinization and minimality. Can it be done more efficient than straighformard way (building a new automata from scratch using respective operations)? There is a paper "Incremental Construction and Maintenance of Minimal Finite-State Automata", but the proposed algorithm allows one to use only string addition/deletion, not arbitrary union/subtraction.