Masami Ito

Shuffle and scattered deletion closure of languages

We introduce and study the notion of shue residual of a language L: the set containing the words whose shue with L is completely included in L. Several properties and a characterization of the shue residual of a language are obtained. The shue closure of a language L (the smallest language that is shue closed and contains L) is investigated. Moreover, conditions for the existence of maximal languages whose shue residual equals a given language are obtained. The paper also considers an operation dual to shue, namely scattered deletion: the scattered deletion of a word w from u consists of the words obtained by sparsely deleting from u the letters of w, in the order in which they appear in w. The scattered deletion residual and scattered deletion closure of a language are dened and studied. Finally, relationships and interdependencies between shue, scattered deletion, and other insertion and deletion operations are obtained. c 2000 Elsevier Science B.V. All rights reserved.

On Some Special Classes of Regular Languages

In [5], the directable non deterministic automata are studied. For non-deterministic automata, the directability can be defined in several ways. In each case considered, the directing words constitute a regular language and one can study the families of such regular languages. In this paper, six classes of regular languages are defined in accordance with the different definitions of directability given in [5], and we investigate the properties of the classes considered.

Some Petri Net Languages and Codes

In this paper, we consider the language over an alphabet T generated by a given Petri net with a positive initial marking, called a CPN language. This language becomes a prefix code over T. We are interested in CPN languages which are maximal prefix codes, called mCPN languages over T. We will investigate various properties of mCPN languages. Moreover, we will prove that a CPN language is a context-sensitive language in two different ways.

Words, Semigroups, and Transductions: Festschrift in Honor of Gabriel Thierrin

Some operators on families of fuzzy languages and their monoids, P.R.J. Asveld liars, demons, and chaos, C.S. Calude et al conditional grammars with restrictions by syntactic parameters, J. Dassow circularity and other invariants of gene assembly in ciliates, A. Ehrenfeucht et al catenation closed pairs and forest languages, C-M Fan and H-J Shyr valence grammars with target sets, H. Fernau and R. Stiebe minimal recognizers and syntactic monoids of DR tree languages, F. Gecseg and M. Steinby visualizing languages using primitive powers, T. Head disjunctivity, H. Jurgensen string operations suggested by DNA biochemistry - the balanced cut operation, L. Kari and A. Pun how to generate binary codes using context-free grammars, L. Kaszonyi generation and parsing of morphism languages by uniquely parallel parsable grammars, J. Lee and K. Morita on the generative power of iterated transductions, V. Manca words, dyck paths, trees, and bijections, H. Prodinger iterated morphisms with complementarity on the DNA alphabet, A. Salomaa topologies for the set of disjunctive w-words, L. Staiger and other papers.

Group weighted finite transducers

Abstract. We consider weighted finite transducers over arbitrary groups, that is finite transducers having a counter in which, at any step, a value of the group is stored but no information regarding the content of this counter is available until the computation is finished. The computation is valid if the counter value is the neutral element of the group. We generalize here some results from [8] and [17].

Multiple keyword patterns in context-free languages

A polynomial algorithm is shown to solve the following problem: Given a context-free language L and a finite list of nonempty words w 1,..., w n , let us decide whether or not there are words z 0,..., z n having z 0 w 1 z 1... w n z n ∈ L(G).