A Complete Integrated NLG System Using AI and NLU Tools

A complete integrated NLG system using AI and NLU tools Laurence Danlos Lattice U. Paris 7, Case 7003 2, place Jussieu 75251 Paris Cedex 05 France danlos@linguist.jussieu.fr Adil El Ghali Lattice U. Paris 7, Case 7003 2, place Jussieu 75251 Paris Cedex 05 France adil@linguist.jussieu.fr Abstract A standard architecture for an NLG system has been defined in (Reiter and Dale, 2000). Their work describes the modularization of an NLG system and the tasks of each module. How- ever, they do not indicate what kind of tools can be used by each module. Nevertheless, we be- lieve that certain tools widely used by the AI or NLU community are appropriate for NLG tasks. This paper presents a complete integrated NLG system which uses a Description logic for the content determination module, Segmented Dis- course Representation Theory for the document structuring module and a lexicalized formalism for the tactical component. The NLG system, which takes into account a user model, is illus- trated with a generator which produces texts explaining the steps taken by a proof assistant. 1 Introduction The standard architecture of an NLG system proposed in (Reiter and Dale, 2000) is repre- sented schematically in Figure 1.1. The tool used by a module and the data structure of its output are not precisely defined. According to Reiter and Dale, they vary from one author to the other. However, we believe that certain tools widely used by the AI or NLU community are appropriate for NLG tasks. Therefore, we reformulate in more specific terms Figure 1.1 as Figure 1.2. The paper describes the modules of Fig- ure 1.2: Section 3 justifies the use of a descrip- tion logic for the content determination task and its ouput, a “message”; Section 4 specifies the use of sdrt for the document structuring task Document structuring à la SDRT Communicative goals Content Determination Document Structuring description logic with a Determination Content Communicative goals Lexicalized Micro−planner Surface Lexicalized Semantic Dependency tree realizer Micro−planner representation Semantic Document Planner Figure 1.1 Standard architecture of an NLG system Tactical component SDRS Figure 1.2 Architecture of an NLG system Document plan message logical form with data structures Text Text Surface realizer and its output, a “document plan”; Section 5 exposes briefly the use of a lexicalized formal- ism in the tactical component. Each section is illustrated with GePhoX, a generator that pro- duces texts which explain the steps taken by PhoX , a proof assistant (Raffalli and Roziere, 2002). GePhoX is presented in Section 2. As this paper intends to present a complete NLG system, there is no room for explaining each module in detail. We refer the reader to (El Ghali, 2001) for the content determination mod- ule, to (Danlos et al., 2001) for the document structuring module and to Danlos (1998; 2000) for the lexicalized tactical component. These goal ∀p, d : N(d ̸= N0 → ∃q, r : N(r < d ∧ p = q ∗ d + r)) 1. intros. 2. elim −4 H well founded.N. …

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