automaton_downwards_closed (960B)
1 # Downwards closed automaton 2 3 Deciding if the language of an [NFA] is [language_downwards_closed] is [PSPACE_complete] even on an alphabet of size 2, cf [karandikar2016deciding] Proposition 7.1. But it is [NL_complete] on [DFAs] 4 5 Testing the [automaton_equivalence] of two [NFAs] recognizing downwards closed languages is [coNP_complete], cf [bachmeier2014finite] 6 7 Ditto for [automaton_inclusion], cf [karandikar2016state] Proposition 7.3 8 9 [automaton_inclusion_downwards_closed] 10 11 All of this holds even if only the right-hand-side [NFA] is upwards-closed, cf also [inclusion_DFA_trick] 12 13 [universality_automaton_downwards_closed] 14 15 See also: [automaton_upwards_closed] 16 17 Up: [language_downwards_closed] 18 19 Aliases: downwards closed automaton, downwards closed automata, subword closed automaton, subword closed automata, automaton subword closed, subsequence closed automaton, subsequence closed automaton, automaton subsequence closed, automata subsequence closed