SETS OF DOCUMENTS USING FUZZY SET TECHNIQUES

Ordered sets of documents are encountered more and more in information distribution systems, such as information retrieval systems (IRS). Classical similarity measures for ordinary sets of documents hence need to be extended to these ordered sets. This is done in this paper using fuzzy set techniques. First a general similarity measure is developed which contains the classical strong similarity measures such as Jaccard, Dice, Cosine and which contains the classical weak similarity measures such as Recall and Precision. Key Words: similarity measure, ordered set, fuzzy ' Permanent address. Then these measures are extended to comparing fuzzy sets of documents. Measuring the similarity for ordered sets of documents is a special case of this, where, the higher the rank of a document, the lower its weight is in the fuzzy set. Concrete forms of these similarity measures are presented. All these measures are new and the ones for the weak similarity measures are the first of this kind (other strong similarity measures have been given in a previous paper by Egghe and Michel). Some of these measures are then tested in the IR-system Profil-Doc. The engine SPIRIT" extracts ranked documents sets in 3 different contexts, each for 600 request. The practical useability of the OS-measures is then discussed based on these experiments. I