Accession Number : AD0683684

Title :   WEB GRAMMARS.

Descriptive Note : Technical rept.,

Corporate Author : MARYLAND UNIV COLLEGE PARK COMPUTER SCIENCE CENTER

Personal Author(s) : Pfaltz,John L. ; Rosenfeld,Azriel

Report Date : JAN 1969

Pagination or Media Count : 42

Abstract : Classes of 'phrase-structure grammars' are defined whose 'languages' consist, not of strings of symbols, but of directed graphs with symbols at their vertices ('webs'). Examples of such 'web grammars' are given, having languages consisting of trees, of two-terminal series-parallel networks, and of 'triangular' networks. It is shown that if the graphs permitted in a 'context-sensitive' web grammar are required to be acyclic, and the parsing rules are assumed to be graph homomorphisms, then any subgraph which is parsed by a rule must be 'convex', and any rule is a composite of rules each of which parses a subgraph having just two points. (Author)

Descriptors :   (*PHRASE STRUCTURE GRAMMARS, GRAPHICS), NETWORKS, SYMBOLS, COMPUTATIONAL LINGUISTICS, SET THEORY

Subject Categories : Linguistics

Distribution Statement : APPROVED FOR PUBLIC RELEASE