Language production

David D. McDonald
1981 Proceedings of the 19th annual meeting on Association for Computational Linguistics -  
Ultimately in any natural language production system the largest amount of human effort will go into the construction of the dictionary: the data base that associates objects and relations in the program's domain with the words and phrases that could be used to describe them. This paper describes a technique for basing the dictionary directly on the semantic abstraction network used for the domain knowledge itself, taking advantage of the inheritance and specialization machanisms of a network
more » ... rmalism such as r,L-ON~ The technique creates eonsidcrable economies of scale, and makes possible the automatic description of individual objects according to their position in the semantic net. Furthermore, because the process of deciding what properties to use in an object's description is now given over to a common procedure, we can write general-purpose rules to, for example, avoid redundancy or grammatically awkward constructionS. Regardless of its design, every system for natural !anguage production begins by selecting objects and relations from the speaker's internal model of the world, and proceeds by choosing an English phrase to describe each selected item, combining them according to the properties of the phrases and the constraints of the language's grammar and rhetoric. TO do this, the system must have a data base of some sort, in which the objects it will talk about are somewhow associated with the appropriate word or phrase (or with procedures that will construct them). 1 will refer to such a data base as a dictionary. The ~nctional labels marking the constituent positions (i.e. "subject", "verb", ccc.) control the options for the realization of the domain-network objects they initially con=in. (The objects will be subscquendy replaced by the phrases that reafizc thcm. processing from leR to righc) Thus the first instance of S/I)CI_ in the subject position, is realized without contextual effects as the name ".V/DCL": while the second instance, acting as the reladve pronoun fur the cleft, is realized as the interrogative pronoun "where": and the final instance, embedded within the "next-state" relation, is suprcsscd entirely even though the rest of the relation is expre.~cd normally. These cnutextoal variations are all entirely transparent to the dictionary mechanisms and demonstrate how we can increa~ the utility of the phrases by carefully annotating them in the dictionary and using general purpose operations chat are ~ggered by the descriptions of the phrases alone, therefore not needing to know anything about their semant~ content. This example was of contextual effects that applied aRer the domain objects had been embedded in a linguistic structure, l.inguis~c context can have its effect eadier as well by monitoring the aecumuladon p~occ~ and appiyiog its effects at that level. Considering how the phrase for the jump are C2.05 would be fonned in this same example. Since the planner's original insmaction (i.e. "(say-abm,t_ )" did not mention C205 spccifcally, the description of that ubjec~ will be IeR to the default precis discussed earlier. In the original example, C205 was dc~ribed in issoladon, her= it L~ part of an ongoing dJscou~e context which muse be allowed ru influence the proton. The default description employed all three of the domain-network relations that C205 is involved in. In this discourse context, however, one of those relations, "neat-smte(c2OS)=SIDCL". has already be given in the text: were we to include it in this realization of C'205. the result would be garishly redundant and quite unnatural, i.e. "3/DCL ~ where the jump arc from S/NP Io S/DCL goes to". To rule out this realization, we can filterttm original set of three relations, eliminating the redundant relation bemuse we know that it is already mentioned in the CCXL Doing this en~ils (1) having some way to recognize when a relauon is already given in the text. and (2) a predictable point in the preec~ when the filtering can be done. rha second is smaight fo~arcL the "describe-as" fimetion is the interface between the planner and the re',dization components; we simply add a cheek in t~t function to scan through the list of relation-entries to bc combined and arrange for given relations to be filtered ouc. As fi)r the definition of "given". MUMBLE maintains a multi-purpose record of the cunmnt discourse context which, like the dictionary, is a rectalevel network describing the original speaker's network from yet this other point of view. Nlem-links connect relations in the speaker's network with the mics they currendy play in ~be ongoing discourse, as illustrated in figure five. l~te definition of "give n" in terms of properties defined by discou~e
doi:10.3115/981923.981940 dblp:conf/acl/McDonald81 fatcat:sznqy6mn7nayrgmcrtdjaokdxi