A Parsing Algoritm That Extends Phrases

It is desirable for a parser to be able to extend a phrase even after it has been combined into a larger syntactic unit. This paper presents an algorithm that does this in two ways, one dealing with "right extension" and the other with "left recursion". A brief comparison with other parsing algorithms shows it to be related to the left corner parsing algorithm, but it is more flexible in the order that it permits phrases to be combined. It has many of the properties of the sentence analyzers of Marcus and Riesbeck, but is independent of the language theories on which those programs are based.