A Simple Probabilistic Approach to Classification and Routing

A SIMPLE PROBABILISTIC APPROACH TO CLASSIFICATION AND ROUTING Louise Guthrie / James Leistensnider Lockheed Martin Corporation P.O. Box 8048 Philadelphia, PA 19101 guthrie,leistens@mds.lmco.com 1. ABSTRACT Several classification and routing methods were im- plemented and compared. The experiments used FBIS documents from four categories, and the measures used were the ff.idf and Cosine similarity measures, and a maximum likelihood estimate based on ass~lming a Multinomial Distribution for the various topics (popula- tions). In addition, the SMART program was run with 'lnc.ltc' weighting and compared to the others. Decisions for both our classification scheme (docu- ments are put into any number of disjoint categories) and our routing scheme (documents are assigned a 'score' and ranked relative to each category) are based on the highest probability for correct classification or routing. All of the techniques described here are fully automatic, and use a training set of relevant documents to produce lists of distin~i~hin£ terms and weights. All methods (ours and the ones we compared to) gave excel- lent results for the classification task, while the one based on the Multinomial Distribution produced the best results on the routing task. 2. INTRODUCTION One of the goals of the TIPSTER Phase H Extraction Project [Contract Number 94-F133200-000] has been to integrate extraction and detection technologies. In this paper we extend previous work (Guthde, et al) [1] on classifying texts into categories, and develop a meth- odology based on the classification technique for rout- ing documents. By classifying and routing texts into categories we mean to include a variety of applications; categorizing texts by topic, by the language the text is written in, or by relevance to a specified task. The techniques used here are not language specific and can be applied to any language or domain. 2.1. The Intuitive Model The mathematical model we use in this paper for- maliTes the intuitive notion that humans can identify the topic of an UlffamilJar article based on the occurrence of topic specific words and phrases. Note that most people can tell that the first passage below is about music, even though the word 'music' is not in the passage. Similarly, most people can tell that the second passage is from a sports article, even though the word 'sport' is never mentioned. "Before the release of his last studio album, 1993"s 'Ten Summoner's Tales', Sting commented that he could no longer put his whole heart into his work; it left him feeling too vulnerable. Not surprisingly, that disc was well-crafted, but a bit void of feeling--unfortunate, considering the wondrous synergy of heart and craft on Sting's masterwork, 1987's 'Nothing Like the Sun'. Sadly, 'Mercury Falling' makes 'Ten Summoner's Tales' seem brilliant by comparison, lf s as if Sting only made it because he looked at his calendar one day and real- ized, by golly, that it was time to make another record. Easily the worst album of what has until now been a re- markably successful career, the disc is aptly named: the temperature never seems to rise …

Content truncated to 500 words