Coordination Between Logical Agents

Abstract

In this paper we suppose an agent that has a knowledge base written in logic programming and sets of beliefs under the answer set semantics. We then consider the following two problems: given two logic programs P ₁ and P ₂, which have the sets of answer sets $\mathcal{AS}(P_1)$ and $\mathcal{AS}(P_2)$, respectively; (i) find a program Q which has the set of answer sets such that $\mathcal{AS}(Q)$ = $\mathcal{AS}(P_1) \cup \mathcal{AS}(P_2)$; (ii) find a program R which has the set of answer sets such that $\mathcal{AS}(R)$ = $\mathcal{AS}(P_1) \cap \mathcal{AS}(P_2)$. A program Q satisfying the condition (i) is called generous coordination of P ₁ and P ₂; and R satisfying (ii) is called rigorous coordination of P ₁ and P ₂. Generous coordination retains all of the original belief sets of each agent, but admits the introduction of additional belief sets of the other agent. By contrast, rigorous coordination forces each agent to give up some belief sets, but the result remains within the original belief sets for each agent. We provide methods for constructing these two types of coordination and discuss their properties.