The information age is characterizedby a rapid growth in the amountof information availablein electronicmedia. Traditional data handling methods are not adequate to cope with this information flood. KnowledgeDiscovery in Databases(KDD) is a new paradigm that focuses on computerizedexploration of large amounts of data and on discovery of relevant and interesting patterns within them. While most work on KDD is concerned with structured databases, it is clear that this paradigm is required for handling the huge amount of information that is available only in unstructuredtextual form. To apply traditional KDD on texts it is necessaryto impose somestructure on the data that would be rich enoughto allow for interesting KDD operations.On the other hand, we have to consider the severe limitations of current text processing technology and define rather simple structures that can be extracted from texts fairly automatically and in a reasonable cost. We propose using a text categorization paradi...