AIR/X - a Rule-Based Multistage Indexing System for Large Subject Fields

Abstract

AIR/X is a rule-based system for indexing with terms (descriptors) from a prescribed vocabulary. For this task, an indexing dictionary with rules for mapping terms from the text onto descriptors is required, which can be derived automatically from a set of manually indexed documents. Based on the Darmstadt Indexing Approach, the indexing task is divided into a description step and a decision step. First, terms (single words or phrases) are identified in the document text. With term-descriptor rules from the dictionary, descriptor indications are formed. The set of all indications from a document leading to the same descriptor is called a relevance description. A probabilistic classification procedure computes indexing weights for each relevance description. Since the whole system is rule-based, it can be adapted to different subject fields by appropriate modifications of the rule bases. A major application of AIR/X is the AIR/PHYS system developed for a large physics database. This application is described in more detail along with experimental results.