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Báo cáo khoa học: "A Generalised Two-Level System"
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This paper presents a generalised twolevel implementation which can handle linear and non-linear morphological operations. An algorithm for the interpretation of multi-tape two-level rules is described. In addition, a number of issues which arise when developing non-linear grammars are discussed with examples from Syriac. | SEMHE A Generalised Two-Level System George Anton Kiraz Computer Laboratory University of Cambridge St John s College Email George.KirazScl.cam.ac.uk URL http www. cl. cam. ac. uk users gkl05 Abstract This paper presents a generalised two-level implementation which can handle linear and non-linear morphological operations. An algorithm for the interpretation of multi-tape two-level rules is described. In addition a number of issues which arise when developing non-linear grammars are discussed with examples from Syriac. 1 Introduction The introduction of two-level morphology Kosken-niemi 1983 and subsequent developments has made implementing computational-morphology models a feasible task. Yet two-level formalisms fell short from providing elegant means for the description of non-linear operations such as infixation circumfix-ation and root-and-pattern morphology.1 As a result two-level implementations - e.g. Antworth 1990 Karttunen 1983 Karttunen and Beesley 1992 Ritchie et al. 1992 - have always been biased towards linear morphology. The past decade has seen a number of proposals for handling non-linear morphology 2 however none Supported by a Benefactor Studentship from St John s College. This research was done under the supervision of Dr Stephen G. Pulman. Thanks to the anonymous reviewers for their comments. All mistakes remain mine. Although it is possible to express some classes of non-linear rules using standard two-level formalisms by means of ad hoc diacritics e.g. infixation in Antworth 1990 p. 156 there axe no means for expressing other classes as root-and-pattern phenomena. 2 Kay 1987 Kataja and Koskenniemi 1988 Beesley et al. 1989 Lavie et al. 1990 Beesley 1990 Beesley 1991 Kornai 1991 Wiebe 1992 Pulman and Hepple 1993 Narayanan and Hashem 1993 and Bird and Ellison 1994 . See Kiraz 1996 for a review. apart from Beesley s work seem to have been implemented over large descriptions nor have they provided means by which the grammarian can develop .