A System for Transformational Analysis

i I 7 L, m 1965 International Conference on Computational Linguistics A SYSTEM FOR TRANSFOP~ATIONAL ANALYSIS Susumu Kuno The Computation Laboratory Harvard University Cambridge,~assachusetts 02138 ' r., r r /,,~~ ~"~, ~.\ \ ~,~,. ~;~ ,,~: _~ .I Kuno-i ABSTRACT A system is proposed here for assigning a derived P-marker to a given transformed sentence and obtaining the corresponding base P-marker at the same time. Rules of analytical phrase-structure grammar for such a system have associated with them i~formation pertaining to the transfor- mational histories of their own derivation. When a phrase-structure analysis of the sentence is obtained, the set of grammar rules used for the analysis contains all the information necessary for the direct mapping of the derived P-marker into the corresponding P-marker. The system can also be used for decomposing a given complex sentence into "kernel" sentences for the purpose of structure matching between a query sentence and stored document sentences in information retrieval. An experimental program for the proposed system has been written and is currently tested with a small sample grammar. Study is underway to see if there is any mechanical procedure for obtaining an smalytical phrase structure grammar of the proposed type for a given transformational grammar. Kuno-1 A SYSTEM FOR TRANSFORMATIONAL ANALYSIS Susumu Kuno i. Introduction Numerous systems for the automatic recognition procedures of context-free languages have been proposed: 1 among them, two systems are in operation with comparatively large English grammars. One is J. Robinson's English parser 2 based on J. Cocke's algorithm, 3 and the other is the Kuno-Oettinger predictive analyzer of English. 4'5,6 The proponents of neither of the two systems have been satisfied with simply assigning phrase-structure descriptions to each given sentence. A paraphrasing routine has bec~ ~i(~d to Robinson's English parser 7 so that a set of kernel sentences can be obtained in addition to the phrase- structure description of the sentence. For example, the analysis outputs of "X commands the third fleet." "The third fleet is commanded by X." and"X is commander of the third fleet." would all contain the information that the kernel is "S -- X, V -- cQmmands, 0 -- third fleet". In connection with the Kuno-Oettinger predictive analyzer, three kernelizing routines have been proposed by J. Olney, 8 B. Carmody and P. Jones, 9 and D. Foster, lO which accept as input the output of the predictive analyzer and produce either kernel sentences or pairs of words which are in certain defined syntactic relationships. The SMART information retrieval system, ll,12,13,14,1~ Salton's Magic Automatic Retriever of ~exts, has a routine which compares the structure diagram (part of the analysis output of the predictive ~his ~ork has been supported in ~srt by the N~tional Science Founds tion under Gr~nt GN-329. Kuno-2 analyzer) of a request sentence with the structure diagrams of sentences to be retrieved, so that paraphrases of the same kernel sentence can be identified. The aim of the present paper is to investigate the role of the predictive analyzer in a transformational grammar recognition …

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