The basic technique that lies behind the Summariser is very robust, giving it the ability to work on any text, independent of subject. Our evaluations have confirmed that the Summariser works well regardless of the subject area. In general, the Text Summariser works best on factual articles with a reasonably single theme - articles in newspapers, technical journals etc are all good subjects. Two areas which we know are more difficult for the Summariser are lists and narrative works. All we can do to summarise them further is to pick out the most important items, and this requires much more knowledge and understanding than the Summariser possesses.
Some lists are obvious - when they are introduced by bullet points, for example.
However, there are also some more subtle forms of list. Some articles, particularly in legal and medical fields, consist largely of a series of example cases - effectively a list. Summaries of this type of article are generally less effective than average. In the context of the WWW, this means that home pages and index pages which consist of a list of other pages are not good candidates for summarisation. Even if the contents of the text are not a list, html listing tags may have been used to format the whole text for the WWW in a certain way.