Repairing Reference Identification Failures by Relaxation

REPAIRING REFERENCE IDENTIFICATION FAILURES BY RELAXATION Bradley A. Goodman BBN Laboratories I0 Moulton Street Cambridge. Mass. 02238 ABSTRACT The goal of thls work is the enrichment of human-machlne mteractIons in a natural language envlronment. 1 We want to provide a framework less restrictive than earlier ones by allowing a speaker leeway tn forming an utterance about a task and in determining the conversational vehicle to deliver it, A speaker and listener cannot be assured to have the same beliefs, contexts, backgrounds or goals at each point in a conversation. As a result, dlfflcultles and mistakes arise when a listener interprets a speakers utterance. These mistakes can lead to various kinds of mlsunderstandlngs between speaker and hstener. including reference failures or failure to understand the speaker's mtentlon. We call these mtsunderstandlngs mlscommunmatlon Such m~stakes constitute a klnd of "ill-formed" input that can slow down end possibly break down communication. Our goal ~s to recognize and Isolate such mlscommunlcattons and circumvent them. Thls paper will hlghhght a particular class of mlscommunlcatlon - reference problems - by descrlbmg a case study, includlng techniques for avoldlng failures of reference I Introduction Cohen, Perrault and Allen showed in thelr paper "Beyond Question Answering" [8~ that ",.. users of cluestlon-answerzng systems expect them to do more than just answer isolated questions -- they expect systems to engage tn conversation. In doing ~o, the system ts expected to allow users to be less than meticulously hteral ~n conveying their zntentlons, and tt is expected to make hnguxstlc and pragmatic use of the previous discourse." Following in thelr footsteps, we want to build robust natural language processing systems that can detect and recover from mlsc~mmunlcatton. The development of such systems requires s study on how people communicate and how they recover from problems In communication. This paper summarizes the results of a dissertation [13] that tnvestlgates the kinds of mlscommunlcatlon that occur in human communication with a special emphasis on reference prooiems, i.e.. problems a listener has determining whom or what a speaker ts talking about. We have written computer programs and algorithms that demonstrate h~w one could handle such problems m IThis reseorcn was suDDorted in port by the Oefenee Advonce4 Reseorch Pro~ect Aqency under ¢ontr=ct Neee14--77-- C-~378. the context of a natural language understand2ng system. The study of mzscommunlcatlon is a necessary task wlthm such a context since any computer capable of communlcat~ng with humans tn natural language must be tolerant of the tmprecIse, lll-devlsed or complex utterances that people often use. Our current research [25, 26] views most dialogues as being cooperatlve and goal directed, l,e.. a speaker and hstener work together to achieve a common goal. The interpretation of an utterance involves Identifying the underlying plan or goal that the utterance reflects [5. I, 23]. Thls plan, however, is rarely, d ever, obvious at the surface sentence level. A central issue In the interpretation of utterances ts the transformation of sequences of imprecise, zll- devised or complex utterances into well-speclhed plans that might be …

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