Showing papers on "Deterministic pushdown automaton published in 1971"

Characterizations of Pushdown Machines in Terms of Time-Bounded Computers

Abstract: A class of machines called auxiliary pushdown machines is introduced. Several types of pushdown automata, including stack automata, are characterized in terms of these machines. The computing power of each class of machines in question is characterized in terms of time-bounded Turing machines, and corollaries are derived which answer some open questions in the field. ~

Stochastic Automata, Stochastic Languages and Pattern Recognition

Abstract: This paper describes some relations between stochastic automata and stochastic languages, and the possible application of stochastic languages to pattern recognition problems. Stochastic finite-state and stochastic context-free languages are defined. The problem of probability assignment in stochastic languages is discussed. The properties of stochastic finite automata and stochastic pushdown automata used as acceptors are investigated. The use of formal languages in pattern recognition problems is illustrated. The potential application of stochastic languages for pattern description is demonstrated, and the possibility of employing stochastic automata as pattern classifiers is discussed.

Computation by multi-head finite automata

Abstract: Families of languages recognized by multi-head writing finite automata are considered. For n≥1, an n-head writing finite automaton (n-wfa) is a finite state device with n one-way read-write heads on a single input tape. Relationships between families of languages recognized by n-wfa (Wn) and other models (e.g. n-head nonwriting finite automata, linear-bounded automata, and real-time buffer automata) are established. A complexity measure is defined for computations by two-head writing finite automata. This measure is obtained from a sequence which encodes the motion of the two heads. A relationship between complexity classes for 2-wfa and one-tape off-line Turing machines is then derived. Using this relationship, a number of sets are shown to be unrecognizable by any 2-wfa. The incomparability of W2 and families of languages recognized by pushdown automata, n-head pushdown automata, and one-way stack automata is thereby established.

Characterizations and extensions of pushdown translations

Abstract: A device called a pushdown assembler has been recently introduced and has been shown capable of defining exactly the syntax directed translations (SDT's). The output operation of the pushdown assembler can be extended in a natural way to obtain a more powerful device called a type B pushdown assembler (or B-machine). A B-machine can define SDT's more simply and directly than the original pushdown assembler. B-machines can also define many interesting translations which are not SDT's. In this paper the B-machine is defined and compared with the original pushdown assembler. The properties of B-machine translations are investigated and it is shown that, as with SDT's, there exists a natural infinite hierarchy of B-machine translations.