Preference and Priorities: A Study Based on Contrction

Preference models lie at the core of the formalization for several related notions, such as non-monotonic reasoning,obligations, goals, beliefs, etc. Recently, the interest in integrating dynamic operators in the logics of belief, preference and obligation has gained momentum.This integration sheds light on similarities among several change operations traditionally studied independently of each other. While a prolific approach, important operations, such as the well-known contraction of beliefs or derogation of norms studied in the AGM tradition,have not received proper attention in this framework.In this work, we study codifications of contraction operations, stemming from the work on iterate dbelief change, in the logic of preferences, by means of both semantically defined operations and their counterpart in syntactical priority structures.