1 A Top-down, depth-first, left-to-right parser

The following pages provide the Prolog code for a simple top-down, depth-first left-to-right parser. There are two versions of the parser

1. one that just recognises whether a string of words is a well-formed instance of a given syntactic category, and
2. one that also builds a parse-tree for the analysis

Both parsers use a grammar, which should be consulted first, because the file contains the definition of ==> as on operator, which also appears in the parser code.

The code can be saved to your filespace by saving the web page as text and giving it a suitable name with a .pl extension.