Pier Paolo Pisani

A syntactic parser is described for hierarchical concatenation patterns that are presented to the analyzer in the form of linear strings. Particular emphasis is given to the system of “significant addresses” by means of which processing times for large-scale matching procedures can be substantially reduced. The description makes frequent use of examples taken from the fully operational implementation of the parser in an experimental English sentence analyzer. By structuring an area of the computer's central core storage in such a way that the individual locations of bytes and bits come to represent the data involved in the matching procedure, the shifting of information is reduced to a minimum, and the searching of lists is eliminated altogether. The matches are traced by means of binary masks and the state of single bits determines the operational flow of the procedure. The method could be implemented with any interpretive grammar, provided it can be expressed by the functional classification of the items composing the input hierarchical structures.