Natural Language Input for Scene Generation

NATURAL LANGUAGE INPUT FOR SCENE GENERATION M Giovanni Adorni, Mauro Di Manzo Istituto di Elettrotecnica, University of Genoa Viale F.Causa 13, 16145 Genoa, Italy Giacomo Ferrari Istituto di Linguistica Computazionale, CNR Via della Faggiola, 56100 Pisa, Italy ABSTRACT In this paper a system which understands and conceptualizes scenes descriptions in natural language is presented. Specifically, the following components of the system are described: the syntac- tic analyzer, based on a Procedural Systemic Gram- mar, the semantic analyzer relying on the Conceptu- al Dependency Theory, and the dictionary. I INTRODUCTION In this paper a system is presented, which under stands and conceptualizes scenes descriptions in natural language (Italian) and produces simple stat ic images of the scenes. It is part of a larger project that aims at understanding the description of static scenes, reasoning (in case of incom- pleteness or inconsistency) and dialoguing about them, and finally generating and displaying them. The Input Analyzer (IA) of the system is the most stable end experimented component and it is the topic of this paper. It consists of a Syntactic Analyzer, a Cognitive Data Base (CDB) and a Seman- tic Interpreter. II SYNTACTIC ANALYZER The syntactic analysis is performed by means of a Procedural Systemic Grammar (PSG) (McCord,77). The main characteristics of the PSG parser is that the operation flow is highly structured, since different levels of the analysis are associated to the syntactic units of the sentence. Five processes can be activated (CLAUSE, COMPL.GR, NOUN.GR, ADJ.GR and VERB.GR) devoted to recognize respectively: (i) the sentences, (ii) the propositional phrases, comparatives, quantification and noun phrases, (iii) the components of the noun phrases, (iv) the adjectives and their modifiers, (v) the verb and its modifiers. Fig.l shows how these processes can interact in our parser: double arrows indicate message passing and Work supported by M.P.I. under grant 27430/81 single I CLAUSE [.- ,.1 ........ ...... ............ h ! v--.o. arrows indicate reading from input. Each I N°UN'G"~I-'- I i ADJ.GR I- I- ® Fig.l - Levels of Syntactic Analysis level is activated by the superior one, as shown in Fig.l, and returns to its caller the results of its computation as a message. A feature network is associated to each process, which is activated together with its corresponding processes. In a PASCAL-like language the feature network can be defined as follows: type FEATURE .... (.LIST OF FEATURES.)...; LINK=^NODE; NODE=record NAME:FEATURE; VALUE:boolean; FATHER,NEXT_BROTHER:LINK; FIRST_SON,ALTERNAT:LINK; end; FEATURE NETWORK:array(FEATURE) of LINK; Each NODE represents s feature identified by its NAME; the ALTERNATE pointer allows the connection in a Circular list of mutually exclusive features as in SHRLDU (Winograd,72). Each process gives as output a fragment of the FEATURE NETWORK manipu- lated to describe the input; this is performed by means of a set of functions which test the presence 175 of a feature in the FEATURE_NETWORK, add and erase features, as described in McCord ('77). The process is divided into a set of sequential routines,called SLOTs, analyzing the functional components of a Syntactic Unit. In the function: …

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