An Optimistic Model for Searching Web Directories

Web directories are taxonomies for the classification of Web documents using a directed acyclic graph of categories. This paper introduces an optimistic model for Web directories that improves the performance of restricted searches. This model considers the directed acyclic graph of categories as a tree with some “exceptions”. The validity of this optimistic model has been analysed by developing and comparing it with a basic model and a hybrid model with partial information. The proposed model is able to improve in 50% the response time of a basic model, and with respect to the hybrid model, both systems provide similar response time, except for large answers. In this case, the optimistic model outperforms the hybrid model in approximately 61%. Moreover, in a saturated workload environment the optimistic model proved to perform better than the basic and hybrid models for all type of queries.