Prioritized Goals and Subgoals in a Logical Account of Goal Change – A Preliminary Report

Abstract

Abstract. Most previous logical accounts of goal change do not deal with prioritized goals and do not handle subgoals and their dynamics properly. Many are restricted to achievement goals. In this paper, we develop a logical account of goal change that addresses these deficiencies. In our account, we do not drop lower priority goals permanently when they become inconsistent with other goals and the agent's knowledge; rather, we make such goals inactive. We ensure that the agent's chosen goals/intentions are consistent with each other and the agent's knowledge. When the world changes, the agent recomputes her chosen goals and some inactive goals may become active again. This ensures that our agent maximizes her utility. We also propose an approach for handling subgoals and their dynamics. We prove that the proposed account has some intuitively desirable properties.

Logical Foundations for a Rational BDI Agent Programming Language (Extended Version)

“…SubGoal(ψ, φ, s)) iff there is a G-accessibility level n in s such that φ is a p-goal at n while ψ is not, and for all G-accessibility levels in s where ψ is a p-goal, φ is also a p-goal. See [15,11] for details of our formalization of subgoals.…”

“…Our framework combines ideas from the situation calculus-based Golog family of APLs (e.g. [6]), our expressive semantic formalization of prioritized goals, subgoals, and their dynamics [13,15], and work on BDI APLs. We ensure that the agent's chosen declarative goals and adopted plans are consistent with each other and with the agent's knowledge.…”