Modeling preferences on resource consumption and production in ASP

Recently we have proposed RASP, an extension of Answer Set Programming that permits declarative specification and reasoning on consumption and production of resources. Resources are modeled by introducing amount-atoms, involving quantities that represent the available amount of resources. Processes that use resources are easily described through program rules and solutions correspond to different possible allocations of available resources. In this paper, we extend this framework to allow the declarative specification of preferences among alternative use of different resources. We provide semantics for the resulting system and sketch a possible implementation based on standard ASP-solvers. The implementation consists of a standard translation of each rule into a set of plain ASP rules and of an inference engine that manages the firing of rules, the allocation of resources, the satisfaction of user constraints on resource usage. The preferences expressed on resource usage induce a preference order on answer sets. In this initial implementation, such an order is rendered through optimization features provided by standard ASP-solvers.