Has portfolio theory got any principles?

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Guido Zuccon, Leif Azzopardi, C.J. "Keith" van Rijsbergen

Published: 19 Jul 2010, Last Modified: 23 Jan 2026SIGIR '10 Proceedings of the 33rd International ACM SIGIR Conference on Research and Development in Information RetrievalEveryoneRevisionsBibTeXCC BY-SA 4.0
Abstract: Recently, Portfolio Theory (PT) has been proposed for Information Retrieval. However, under non-trivial conditions PT violates the original Probability Ranking Principle (PRP). In this poster, we shall explore whether PT upholds a different ranking principle based on Quantum Theory, i.e. the Quantum Probability Ranking Principle (QPRP), and examine the relationship between this new model and the new ranking principle. We make a significant contribution to the theoretical development of PT and show that under certain circumstances PT upholds the QPRP, and thus guarantees an optimal ranking according to the QPRP. A practical implication of this finding is that the parameters of PT can be automatically estimated via the QPRP, instead of resorting to extensive parameter tuning.