Hyperintensional Partial Meet Contractions

Formal frameworks for Epistemology need to have enough logical structure to enable interesting conclusions regarding epistemic phenomena and to be expressive enough to model competing positions in the philosophical and logical literature. While beliefs are commonly accepted as hyperintensional attitudes, i.e., epistemic attitudes, which may differ even towards necessarily equivalent sentences, most work on standard epistemic logic has relied on idealised and intensional agents. This is particularly true in the area of AGM-inspired Belief Change. Although a few recent studies investigate hyperintensional models of belief change, few have been well connected to the AGM framework, the main paradigm in the area. This work investigates hyperintensional notions of belief base contraction and belief set contraction, as studied in the AGM framework, and its connections to partial meet contractions. We also provide suitable representation theorems, characterising the constructions by means of rationality postulates.