Showing papers on "Pushdown automaton published in 1975"
TL;DR: Upper bounds, close to known lower bounds, are obtained for the succinctness with which a pushdown automaton, and various restrictions of it, can express equivalent fimte-state machines.
Abstract: It ~S shown that to decide whether the language accepted by an arbitrary deterministic pushdown automaton is LL (k), or whether ~t m accepted by some one-counter or finite-turn pushdown machine, must be at least as difficult as to decide whether it is regular. The regularity problem itself is analyzed in detail, and Stearns' dec~mon procedure for this as improved by one level of exponentiatlon Upper bounds, close to known lower bounds, are obtained for the succinctness with which a pushdown automaton, and various restrictions of it, can express equivalent fimte-state machines
99 citations
TL;DR: The principal result described in this paper is the equivalence of the following statements: every set accepted by a nondeterministic one-way two-head finite automaton can be acceptance by a deterministic two-way k-head infinite automaton.
75 citations
13 Oct 1975
TL;DR: Valiant's decision procedure for equivalence of deterministic finite-turn pushdown machines is improved upon and an algorithm for constructing a suitable function which determines the replacements is obtained.
Abstract: In this paper Valiant's decision procedure for equivalence of deterministic finite-turn pushdown machines is improved upon The improved equivalence test is: Given two mahcines, one constructs a pushdown machine that simulates them simultaneously and accepts a string iff it is accepted by exactly one of them The given machines are equivalent iff the simulating pda accepts the empty language The simulating machine uses its pushdown store to hold the contents of the stores of the two simulated machines In order ot prevent the tops of the two stores to get too far apart the simulating machine sometimes replaces the contents of one of the stores Valiant 1,2 has proved the existence of a suitable function which determines the replacements The crux of this paper is an algorithm for constructing such a function The existence of such an algorithm enables us to calculate an upper bound on the time complexity of the improved algorithm We obtain the results that equivalence of deterministic finite-turn pushdown automata can be tested in super-exponential time and equivalence of deterministic two-tape automata can be tested in exponential time
21 citations
TL;DR: By extracting the basic properties common to the automata appeared in existing literatures, a general formulation of automata with ?
17 citations
TL;DR: Several well-known classes of formal languages, which had up to date only been characterized by grammars, are characterized by this new automaton of complexity.
Abstract: A new automaton, called a contraction automaton of complexity ( n, k ), n > 0, k > 1, is defined, and several well-known classes of formal languages, which had up to date only been characterized by grammars, are characterized by this new automaton.
16 citations
11 citations
01 Jan 1975
TL;DR: The concept of recognition of fuzzy languages by machines such as Turing machines, linear bounded automata, pushdown automata and finite automata is proposed and it is shown that it is a reasonable extension of the ordinary concept of Recognition of languages by Machines.
Abstract: In this paper, we propose the concept of recognition of fuzzy languages by machines such as Turing machines, linear bounded automata, pushdown automata and finite automata. It is shown that it is a reasonable extension of the ordinary concept of recognition of languages by machines. Basic results are given about the recognition theory of fuzzy languages.
9 citations
TL;DR: It is shown that for any of the following types, a 2-way Nested Stack Automaton is equivalent to some 2- way Stack Automata of the same type: Deterministic, Nondeterministic, k-head, L(n)-tape-bounded Auxiliary.
9 citations
01 May 1975
TL;DR: A unified approach is presented to deal with automata having different kinds of peripheral devices, leading to homomorphic characterization of language families generated by a single language by finite transduction.
Abstract: A unified approach is presented to deal with automata having different kinds of peripheral devices. This approach is applied to pushdown automata and Turing machines, leading to elementary proofs of several well-known theorems concerning transductions, relationship between pushdown automata and context-free languages, as well as homomorphic characterization and undecidability questions. In general, this approach leads to homomorphic characterization of language families generated by a single language by finite transduction.
8 citations
TL;DR: It is shown that every random environment discussed up to the present is a special case of this machine and the system consisting of this environment and an automaton is equivalent to an autonomous stochastic automaton.
5 citations
TL;DR: It is shown that every set acceptable by such a machine within time boundc⋅np,p ∈ ℕ, is accepted by a deterministic 2p-head two-way pushdown automaton which has additional counters of length log2n.
Abstract: In this paper a machine model is defined whose access to the storage cells is controlled by means of address registers. It is shown that every set acceptable by such a machine within time boundc⋅np,p ∈ ℕ, is accepted by a deterministic 2p-head two-way pushdown automaton which has additional counters of length log2n. On the other hand every set acceptable by a deterministicp-head two-way pushdown automaton can be accepted by this machine model within time boundc⋅np⋅log2n.
10 Sep 1975
TL;DR: This paper explains the general lines of a compiler and especially of the part of the compiler which generates code, starting from the output of the syntactic analysis, which is a two stack automaton providing for a mechanism allowing to generate optimized code.
Abstract: This paper explains the general lines of a compiler and especially of the part of the compiler which generates code, starting from the output of the syntactic analysis. This part of the compiler is a two stack automaton providing for a mechanism allowing to generate optimized code.