tailieunhanh - Báo cáo khoa học: "A THREE-LEVEL MODEL FOR PLAN EXPLORATION"

In modeling the structure of task-related discourse using plans, it is important to distinguish between plans that the agent has adopted and is pursuing and those that are only being considered and explored, since the kinds of utterances arising from a particular domain plan and the patterns of reference to domain plans and movement within the plan tree are quite different in the two cases. This paper presents a three-level discourse model that uses separate domain and exploration layers, in addition to a layer of discourse metaplans, allowing these distinct behavior patterns and the plan adoption and reconsideration moves. | A THREE-LEVEL MODEL FOR PLAN EXPLORATION Lance A. Ramshaw Department of Computer Science Bowdoin College Brunswick ME 04011 Internet ramshaw@ ABSTRACT In modeling the structure of task-related discourse using plans it is important to distinguish between plans that the agent has adopted and is pursuing and those that are only being considered and explored since the kinds of utterances arising from a particular domain plan and the patterns of reference to domain plans and movement within the plan tree are quite different in the two cases. This paper presents a three-level discourse model that uses separate domain and exploration layers in addition to a layer of discourse metaplans allowing these distinct behavior patterns and the plan adoption and reconsideration moves they imply to be recognized and modeled. DISCOURSE MODEL LEVELS In task-related discourse much of the discourse structure derives directly from the task structure so that a model of the agent s plans can serve as a useful discourse model with discourse segment boundaries mapping to sub-plan boundaries and the like. This simple model works well in applications like expert-apprentice dialogues where a novice agent is currently pursuing a single domain plan. Since the discourse tracks the domain plan so closely in such cases it is fairly easy to make the links between the agent s queries and the relevant domain plans. But this single-level model is not rich enough to handle phenomena like clarification subdialogues or plan revision as seen in the work of Litman Carberry and others. Litman s model Lit85 LA87 LA90 employs a stack of discourse metaplans on top of the base domain plan producing a two-level model that can handle clarification subdialogues and other discourse phenomena that go beyond the domain plans. Carberry Car90 adds an independent stack of discourse goals for similar reasons. In earlier work Ram89a I explored the use of a different kind of metaplan to model what I called .