Showing papers on "Deterministic pushdown automaton published in 1979"

Linearity is polynomially decidable for realtime pushdown store automata

Abstract: If M is a realtime deterministic pushdown store acceptor, the language L ( M ) accepted by M by final state and empty store is linear context-free if and only if a certain grammar obtained from M is linear context-free. Hence, it is polynomially decidable for realtime deterministic pushdown store automata M whether L(M) is linear context-free. If M is a realtime deterministic pushdown store acceptor and L ( M ) is linear context-free, we can construct a realtime single turn deterministic pushdown store automaton {if27-1} with {if27-2}. Hence “ L ( M ) = L ” is decidable for M a realtime deterministic pushdown store acceptor and L the language accepted by final state by a single turn deterministic pushdown store acceptor.

On relativizing auxiliary pushdown machines

Abstract: We consider relativizing the constructions of Cook in [4] characterizing space-bounded auxiliary pushdown automata in terms of timebounded computers. LetS(n) ≥ logn be a measurable space bound. LetDTA[NTA] be the class of setsS such that there exists a machineM such thatM with oracleA recognizes the setS andM is a deterministic [nondeterministic] oracle Turing machine acceptor that runs in time 2cS(n) for some constantc. LetDBiA[NBiA] be the class of setsS such that there exists a machineM such thatM with oracleA recognizes the setS andM is a deterministic [non-deterministic] oracle Turing machine acceptor with auxiliary pushdown that runs in spaceS(n) and never queries the oracle about strings longer than:S(n) ifi = 1, 2cS(n) for some constantc, ifi = 2, + ∞ ifi = 3.

Strict Deterministic Languages and Controlled Rewriting Systems

Abstract: A controlled rewriting system over an alphabet X is a finite set of rules vi → wi (l⩽i⩽n) with vi , wi in X* such that |vi|<|wi| , each rule being associated with a regular language Ri X* Given such a system, f ⇒ g means that f=αviβ and g=αwiβ for some i, α in Ri , β in X* The system is said to be injective if and only if f ⇒ g ⇐ f′ implies f=f′ Controlled rewriting systems are a special case of finite relations with computable left context (P Butzbach [5], 1973), which can be defined as above, with the Ri's recursive instead of regular P Butzbach proved [5] that every simple deterministic language [11] is generated by some finite relation with computable left context iterating from a finite set of words Here we improve this result with our THEOREM 1 : "Every strict deterministic language is generated by some injective controlled rewriting system iterating from a finite set of words" Moreover, let A be a deterministic pushdown automaton and ⇒ be the rewriting relation associated with A by the above theorem Let θ : X* ⇒ X* defined by θ(u)=v if and ∃ w, w ⇒ v (v is unique, for ⇒ is injective); in some sense, θ generalizes the semi-Dyck simplification We state :

New proofs for jump dpda's

Abstract: The deterministic context-free languages (see e.g. Harrison [5]) constitute an important subfamily of the context-free languages. The need of good parsing algorithms and the intriguing equivalence problem have lead to the investigation of various subfamilies and various characterizations of this family. The deterministic pushdown automata with jumps, jump dpda's in short, establish a useful device of characterizing the deterministic languages.

A Counterexample to Reingold’s Pushdown Permuter Characterization Theorem

Abstract: There is a well-known class of algorithms for permuting symbols which has been formally characterized by a device called a pushdown permuter. A theorem attempting to characterize the type of permutations that can be achieved by a pushdown permuter has appeared in the literature. This paper presents a counterexample to this theorem.