Two Decidability Results for Deterministic Pushdown Automata

Abstract A real-time deterministic pushdown automaton is said to be stack uniform if for each input letter a, every a-tule has the same effect on the length of the pushdown store, i.e., if ( s 1 , A ) → a ( S 2 , w ) and ( s 1 ′ , A ′) → a ( s 2 ′ , w ′) are two a -rules, then the lengths of w and w ′ are equal. It is shown that the equivalence problem for stack uniform automata and the inclusion problem for stack uniform automata with empty store acceptance are decidable.