Combining Logic Programming and Imperative Programming in LPS

Logic programs and imperative programs employ different notions of computing. Logic programs compute by proving that a goal is a logical consequence of the program, or by showing that the goal is true in a model defined by the program. Imperative programs compute by starting from an initial state, executing actions to transition from one state to the next, and terminating (if at all) in a final state when the goal is solved. In this paper, we present the language LPS (Logic Production Systems), which combines the logic programming and imperative programming notions of computing. Programs in LPS compute by using beliefs, represented by logic programs, to model the changing world, and by executing actions, to change the world, to satisfy goals, represented by reactive rules and constraints.