Language-Specific Mappings from Semantics to Syntax

Language-Specific Mappings from Semantics to Syntax Judy Delin Department of English Studies University of Stirling Stirling FK9 4LA U.K. j Idl~st ir. ac. uk Donia R. Scott ITRI University of Brighton Mithras Annexe Lewes Road Brighton BN2 4AT, U.K. drs2@itri, bton. ac. uk Anthony Hartley ITRI University of Brighton Mithras Annexe Lewes Road Brighton BN2 4AT, U.K. afh~it ri. bton. ac. uk Abstract We. present a study of the mappings from semantic content to syntactic ex- pression with the aim of isolating the precise locus and role of pragmatic infor- mation in the generation process, l~om a corpus of English, French, and Por- tuguese instructions for consumer prod- ucts, we demonstrate the range of ex- pressions of two semantic relations, GEN- EI~ATION and ENABLEMENT (Goldman, 1970) in each language, and show how the available choices are constrained syn- tactically, semantically, and pragmati- cally. The study reveals how multilin- gum NLG can be informed by language- specific principles for syntactic choice. 1 Introduction We report here on work which addresses the message-to-syntax mapping in the context of au- tomatic generation of instructional texts the kinds of texts found in the procedural parts of manuMs or information leaflets, pharmaceuticM products. Instructional texts do not simply con- sist of lists of imperatives: instructions may also describe, eulogise, inform and explain. Generating good-quality draft instructions requires a detailed specification of how to map from semantic repre- sentations of the task actions onto a wide range of linguistic expressions. Our corpus is composed of naturally-occurring instructions in the three languages of study. Our overall approach is to obtain different-language drafts that are congruenl with the technical con- tent embodied in the task to be performed (and with other relevant information about the task). A satisfactory level of congruence requires the use of syntactic and pragmatic rules appropriate to each target language, mat)ping fi'om the seman- tics to appropriate expression in a way that is frec from influence from any source language 1. We 1See (Hartley and Paris, 1995) for discussion of the begin the generation process with a plan-based model of the underlying task} In our study, we have looked at two specific procedurM relations that can hold between pairs of actions in a task, identified by the philoso- pher Alvin Goldman as the relations of GENEP~- ATION and ENABLEMENT (Goldman, 1970) re- lations which have the advantage of being tbr- mally specified (see e.g.(Pollack, 1986; Balkanski, 1993)), and need to be expressed regularly within instructional texts. In section 2, we give a brief definition of generation and enablement, before going on in section 3 to describe how the two re- lations are realised in the corpus of Portuguese, English, and French instructions. 2 The Semantic Relations Generation and enablement are relations that can hold between pairs of states, events, processes, or actions. A simple test of generation holding be- tween action pairs is whether it can be said that by performing one of the actions (a) under appro- priate conditions, the other (/9) will …

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