
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 'phrasestructure 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 twoterminal seriesparallel networks, and of 'triangular' networks. It is shown that if the graphs permitted in a 'contextsensitive' 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