Aggregates and Preferences in Logic Programming

The present work proposes a new semantics for logic program with preference rules and studies logic programs enriched with both aggregates and preference rules. The interest of research literature in handling user preferences to express a partial order on rules and literals is reflected by an extensive number of proposals. The association of aggregates and preferences is, here, used to also express a partial order on global models, other than on literals and rules, so that optimization problems can be expressed in a simple and elegant way. The use of aggregates makes logic languages more flexible and intuitive, without any additional computational complexity.