A Global Parser for Context-Free Phrase Structure Grammars
An algorithm for analyzing any context-free phrase
structure grammar and for generating a program 
which can then parse any sentence in the language (or
indicate that the given sentence is invalid) is 
described. The parser is of the "top-to-bottom" type
and is recursive . A number of heuristic procedures 
whose purpose is to shorten the basic algorithm by quickly
ascertaining that certain substrings of the 
input sentence cannot correspond to the target nonterminal
symbols are included.  Both the generating 
algorithm and the parser have been implemented in RCA
SNOBOL and have been tested successfully on a number 
of artificial grammars and on a subset of ALGOL.  A
number of the routines for extracting data about 
a grammar, such as minimum lengths of N-derivable strings
and possible prefixes, are given and may be 
of interest apart from their application in this particular context.
CACM April, 1968
Unger, S. H.
