Reporting exact and approximate regular expression matches

While much work has been done on determining if a document or a line of a document contains an exact or approximate match to a regular expression, less effort has been expended in formulating and determining what to report as the match once such a hit is detected. For exact regular expression pattern matching, we give algorithms for finding a longest match, all symbols involved in some match, and finding optimal submatches to tagged parts of a pattern. For approximate regular expression matching, we develop notions of what constitutes a significant match, give algorithms for them, and also for finding a longest match and all symbols in a match.