Relaxing result accuracy for performance in publish/subscribe systems

Since the evaluation of XPath expressions is highly dependent upon their size and navigational structures that include ancestor-descendant relationships ("//") and wildcard steps ("/*")we introduce a novel and complementary approach to optimizing XPath queries by rewriting and minimizing such structural occurrences. This rewriting approach depends upon the existence of a statistical schema, which we derive from a set of pre-processed XML documents. However, an imprecision in the schema extraction may lead to a loss of accuracy in the results. Through experimentation and analysis, we validate the scalability and efficiency of our approach.