Modelling Word Burstiness in Natural Language: A Generalised Polya Process for Document Language Models in Information Retrieval

Abstract: We introduce a generalised multivariate Polya process for document language modelling. The framework outlined here generalises a number of statistical LLMs used in information retrieval for modelling document generation. In particular, we show that the choice of replacement matrix M ultimately defines the type of random process and therefore defines a particular type of document LLM. We show that a particular variant of the general model is useful for modelling term-specific burstiness. Furthermore, via experimentation we show that this variant significantly improves retrieval effectiveness over a strong baseline on a number of small test collections.