I found a bug in "IncrementalSearch[2]" that can cause wrong results under rare circumstances. One requirement is a "not" search embedded in an "or" search (but this is not sufficient to cause the problem). You find fixed versions at <http://www.dieter.handshake.de/pyprojects/zope> "IncrementalSearch[2]" is a low level search engine for the efficient execution of "and", "or" and "not" queries. Unlike traditional search engines (like that implemented by Zope's ZCatalog), it computes hits incrementally (one at a time) and interleaves hit determination and index lookup. If a query is a quite specific "and" query (that is the usual case), then "IncrementalSearch" can result in significantly reduced search times. I observed gains for "IncrementalSearch2" in an order from about 20 percent for queries including a large (bushy) "or" query (queries "IncrementalSearch2" cannot optimize well) up to 95 percent and more (for pure highly specific "and" queries). -- Dieter