|Title:||Theory Of W-languages; Part I: Characterizations Of W-context Free Languages
|Authors:||Rina S.Cohen and Arie Y.Gold
|Abstract:||An w-language is a set consisting of w-type strings over some alphabet. This paper introduces the basic notions concerning generation of w-languages by means of w-grammars and their recognition by w-machines of various types. Attention is then focused on W-CFL's, the w-languages generated by w-context free grammars. Two main characterizations of the family of W-CFL' s are ob tained: a) An w-language is an w-CFL if and only if n W' t can be represented as .u UiVi' where for each i = l, •••n, Ui and 1-i Vi are context free languages. This result gener4lizes McNaughton's characterization of w-regular languages [Mc]. b) w-CFL' s are precisely the w-languages recognized by w-pushdown automata by designated state sets (and also by "emptying" the pushdown store infinitely many times). A few other characterizations and normal forms for the w-CFL's are given and several decidability results, e.g. the solvability of the emptiness problem, are established.|
|Copyright||The above paper is copyright by the Technion, Author(s), or others. Please contact the author(s) for more information|
Remark: Any link to this technical report should be to this page (http://www.cs.technion.ac.il/users/wwwb/cgi-bin/tr-info.cgi/1975/CS/CS0044), rather than to the URL of the PDF files directly. The latter URLs may change without notice.
To the list of the CS technical reports of 1975
To the main CS technical reports page
Computer science department, Technion