Douglas E. Appelt

AIJ Journal 1993 Journal Article

Interpretation as abduction

• Jerry R. Hobbs
• Mark E. Stickel
• Douglas E. Appelt
• Paul Martin

Abduction is inference to the best explanation. In the TACITUS project at SRI we have developed an approach to abductive inference, called “weighted abduction”, that has resulted in a significant simplification of how the problem of interpreting texts is conceptualized. The interpretation of a text is the minimal explanation of why the text would be true. More precisely, to interpret a text, one must prove the logical form of the text from what is already mutually known, allowing for coercions, merging redundancies where possible, and making assumptions where necessary. It is shown how such “local pragmatics” problems as reference resolution, the interpretation of compound nominals, the resolution of syntactic ambiguity and metonymy, and schema recognition can be solved in this manner. Moreover, this approach of “interpretation as abduction” can be combined with the older view of “parsing as deduction” to produce an elegant and thorough integration of syntax, semantics, and pragmatics, one that spans the range of linguistic phenomena from phonology to discourse structure. Finally, we discuss means for making the abduction process efficient, possibilities for extending the approach to other pragmatics phenomena, and the semantics of the weights and costs in the abduction scheme.

NMR Workshop 1989 Conference Paper

A Non-Monotonic Logic for Reasoning about Speech Acts and Belief Revision

• Douglas E. Appelt
• Kurt Konolige

Abstract A prerequisite to a theory of the way agents understand speech acts is a theory of how their beliefs and intentions are revised as a consequence of events. This process of attitude revision is an interesting domain for the application of nonmonotonic reasoning because speech acts have a conventional aspect that is readily represented by defaults, but that interacts with an agent's beliefs and intentions in many complex ways that may override the defaults. Perrault has developed a theory of speech acts, based on Rieter's default logic, that captures the conventional aspect; it does not, however, adequately account for certain easily observed facts about attitude revision resulting from speech acts. A natural theory of attitude revision seems to require a method of stating preferences among competing defaults. We present here a speech act theory, formalized in hierarchic autoepistemic logic (a refinement of Moore's autoepistemic logic), in which revision of both the speaker's and hearer's attitudes can be adequately described. As a collateral benefit, efficient automatic reasoning methods for the formalism exist. The theory has been implemented and is now being employed by an utterance-planning system.

AIJ Journal 1987 Journal Article

TEAM: An experiment in the design of transportable natural-language interfaces

• Barbara J. Grosz
• Douglas E. Appelt
• Paul A. Martin
• Fernando C.N. Pereira

This article describes TEAM, a transportable natural-language interface system. TEAM was constructed to test the feasibility of building a natural-language system that could be adapted to interface with new databases by users who are not experts in natural-language processing. An overview of the system design is presented, emphasizing those choices that were imposed by the demands of transportability. Several general problems of natural-language processing that were faced in constructing the system are discussed, including quantifier scoping, various pragmatic issues, and verb acquisition. TEAM is compared with several other transportable systems; this comparison includes a discussion of the range of natural language handled by each as well as a description of the approach taken to achieving transportability in each system.

AIJ Journal 1985 Journal Article

Planning english referring expressions

• Douglas E. Appelt

This paper describes a theory of language generation based on planning. To illustrate the theory, the problem of planning referring expressions is examined in detail. A theory based on planning makes it possible for one to account for noun phrases that refer, that inform the hearer of additional information, and that are coordinated with the speaker's physical actions to clarify his communicative intent. The theory is embodied in a computer system called kamp, which plans both physical and linguistic actions, given a high-level description of the speaker's goals.

IJCAI Conference 1983 Conference Paper

A Grammar Formalism for Language Planning

• Douglas E. Appelt

AAAI Conference 1982 Conference Paper

Planning Natural-Language Utterances

• Douglas E. Appelt

This paper describes recent research on a natural-language-generation system that is based on planning. A system named KAMP is described that is capable of producing English sentences as part of a plan to enlist the cooperation of another agent in achieving a goal involving a change in the physical state of the world. The planner uses knowledge about the different subgoals to be achieved and linguistic rules about English to produce sentences that satisfy multiple goals through the realization multiple illocutionary acts.

AAAI Conference 1980 Conference Paper

A Planner for Reasoning about Knowledge and Action

• Douglas E. Appelt