منابع مشابه
Monoid Automata for Displacement Context-Free Languages
In 2007 Kambites presented an algebraic interpretation of Chomsky-Schützenberger theorem for context-free languages. We give an interpretation of the corresponding theorem for the class of displacement context-free languages which are equivalent to well-nested multiple context-free languages. We also obtain a characterization of kdisplacement context-free languages in terms of monoid automata a...
متن کاملInfix Congruences on a Free Monoid
A congruence p on a free monoid X* is said to be infix if each class C of p satisfies u e C and xuy € C imply xy = 1 . The main purpose of this paper is a characterization of commutative maximal infix congruences. These turn out to be congruences induced by homomorphisms t from X* to N° , the monoid of nonnegative integers under addition, with T"1(0) = 1.
متن کاملPerfect Congruences on a Free Monoid
Perfect congruences on a free monoid X* are characterized in terms of congruences generated by partitions of X U {1}. It is established that the upper semilattice of perfect congruences if V-isomorphic to the upper semilattice of partitions on Xu{1}. A sublattice of the upper semilattice of perfect congruences is proved to be lattice isomorphic to the lattice of partitions on X. Introduction an...
متن کاملTest Sets for Context Free Languages and Algebraic Systems of Equations over a Free Monoid
It is shown that for every context free language L there effectively exists a test set F, that is, a finite subset F of L such that, for any pair (g, h) of morphisms, g(x) = h(x) for all x in F implies g(x) = h(x) for all x in L. This result was claimed earlier but a detailed correct proof is given here. Together with very recent results on systems of equations over a free monoid this result im...
متن کاملOn Some Decompositions of r-Disjunctive Languages
Some kinds of decompositions of r-disjunctive languages on an arbitrary alphabet will be investigated. We will show that an f-disjunctive (t-disjunctive) language can be divided into two parts and either one part of them is an f-disjunctive (t-disjunctive) language or both parts are r-disjunctive but not f-disjunctive (t-disjunctive) languages. Finally, a relevant result of H. J. Shyr and S. S....
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ژورنال
عنوان ژورنال: Information and Control
سال: 1977
ISSN: 0019-9958
DOI: 10.1016/s0019-9958(77)80008-9