Formalizing Retrieval Goal Change by Prioritized Circumscription – Preliminary Report –

Abstract

We sometimes encounter a situation during a search over the Internet such that we change a retrieval goal. In this paper, we formalize this phenomena in terms of nonmonotonic reasoning (prioritized circumscription [McCarthy86]). The idea of formalization is as follows. We assume chain of causal rules to satisfy a purpose of the retrieval where bottom conditions are the context of retrieval results and/or retrieval goals such that executing some of the goals make a purpose of the retrieval purpose fulfilled. We also assume a prioritization over causal rules or success predictions of retrieval command which represents strength of satisfaction of rules. Then, given the current context of retrieval results obtained so far, we infer the most preferable retrieval command by prioritized circumscription. We believe that this formalization gives a theoretical basis of what is necessary in an intelligent user navigation tool.