A Generative Grammar Approach for the Morphologic and Morphosyntactic Analysis of Italian

A GENERATIVE GRAMMAR APPROACH FOR THE MORPHOLOGIC AND MORPHOSYNTACTIC ANALYSIS OF ITALIAN Marina Russo IBM Rome Scientific Center via del Giorgione, 129 00147 Rome Italy ABSTRACT A morphologic and morphosyntactic analyzer for the Italian language has been implemented in VM/Prolog 131 at the IBM Romc Scientific Center as part of a project on text understanding. Aim of this project is the development of a prototype which analyzes short narrative texts (press agency news) and gives a formal representation of their "meaning" as a set of first order logic expressions. Question answering features are also provided. The morphologic analyzer processes every word by means of a context free grammar, in order to obtain its morphologic and syntactic characteristics. It also performs a morphosyntactic analysis to recognize fixed and variable sequences of words such as idioms, date cxpressi{~ns, compound tenses of verbs and comparative and superlative form~ of adjectives. The lexicon is stored in a relational data base under thc control of SQL/DS [2], while the endings of the grammar are stored in thc workspace as Proiog facts. A friendly interface written in GDDM [11 allows the uscr to introduce on line the missing lemmata, in order to directly ulxlatc thc dictionary. Introduction About thirty years ago, the development of decripting tccniques made computer scientists be involved for the first time in the field of Linguistics, especially in automatic translation matters. The failure of most of these projects contributed to a general sensibilization towards natural language problems, and gave rise to a variety of formal theories for their treatment. In the last few years, one of the main research objectives ix-came the design of systems able to acquire knowledge directly from fcxts. using natural language as an interface between man and machine. At the IBM Rome Scientific Center a system has been developed for processing Italian texts. The task of the system is to • analyze short narrative texts (press agency news) on a restricted domain (Economics and Finance), • give the formal representation of their "meaning" as a set of first order logic expressions, stored in a knowledge base, • consult this knowledge base in order to answer any qucstlon about the contents of analyzed texts. The system consists of: • a mmphologie analyzer based on a context-free logic grammar with the "word" as axiom and its possible components as terminal nodes. It.includes a lexic9n of about 7000 elementary lemmata, structured in a table of a relational data base under the control of SQL/DS. * a morphosyntaetic analyzer realized by three regular grammars, recognizing respectively compound tenses of verbs (e,g. ha.~ been signed), comparative and superlative forms of adjectives (e.g. Ihe most interesting) and compound numbers (e.g. three billions .~64 millions 234.000). This module reduces the number of possible syntactic relations among the words of the sentence in order to simplify the task of the syntax. * a syntactic parser developed by means of a meta-analyzcr [6[ which aUows to write production rules for attribute gntmmars, and generates from these the …

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