Pattern matching in hypertext

A myriad of textual problems have been considered in the pattern matching field with many non-trivial results. Nevertheless, surprisingly little work has been done on the natural combination of pattern matching and hypertext. In contrast to regular text, hypertext has a nonlinear structure and the techniques of pattern matching for text cannot be directly applied to hypertext. Manber and Wu pioneered the study of pattern matching in hypertext and defined a hypertext model for pattern matching. Subsequent papers gave algorithms for pattern matching on hypertext with special structures - trees and DAGS. In this paper we present a much simpler algorithm achieving the same complexity which runs on any hypertext graph. We then extend the problem to approximate pattern matching in hypertext, first considering hamming distance and then edit distance. We show that in contrast to regular text, it does make a difference whether the errors occur in the hypertext or the pattern. The approximate pattern matching problem in hypertext with errors in the hypertext turns out to be NP-Complete and the approximate pattern matching problem in hypertext with errors in the pattern has a polynomial time solution.