Note that whether a pattern-based system is viewed as a knowledge extraction system or summarization system depends on the text it is applied to. If all the information of interest is bundled together in a single, extended text segment (as in the case of earthquake reports), then the knowledge extracted can be viewed as a summary of the segment. If instead the information is selectively extracted from miscellaneous sentences scattered through large text collections, with most of the material being ignored as irrelevant to the purposes of extraction, then we would view the activity of the system as information extraction rather than summarization.