Consonant Spreading in Arabic Stems

This paper examines the phenomenon of consonant spreading in Arabic stems. Each spreading involves a local surface copying of an underlying consonant, and, in certain phonological contexts, spreading alternates productively with consonant lengthening (or gemination). The morphophonemic triggers of spreading lie in the patterns or even in the roots themselves, and the combination of a spreading root and a spreading pat tern causes a consonant to be copied multiple times. The interdigitation of Arabic stems and the realization of consonant spreading are formalized using finite-state morphotactics and variation rules, and this approach has been successfully implemented in a large-scale Arabic morphological analyzer which is available for testing on the Internet. 1 I n t r o d u c t i o n Most formal analyses of Semitic languages, including Arabic, defend the reality of abstract, unpronounceable morphemes called ROOTS, consisting usually of three, but sometimes two or four. consonants called RADICALS. The classic examples include k t b (~. ,D ~)1, appearing in a number of words having to do with writing, books, schools, etc.; and d r s ( ~ 9 z), appearing in words having to do with studying, learning, teaching, etc. Roots combine nonconcatenatively with PATTERNS to form STEMS, a process known informally as INTERDIGITATION o r INTERCALATION. W e shall look first at Arabic stems in general before examining GEMINATION and SPREADING, related phenomena wherein a single underlying radical is real~The Arabic-script examples in this paper were produced using the ArabTeX package for TEX and DTEX by Prof. Dr. Klaus Lagally of the University of Stut tgart . daras duris darn'as duruus diraasa(t) darraas madrasa( t ) madaar is madras iyy tadri is 'study' 'be studied' 'teach' 'lessons' 's tudy' 'eager student ' 'school' 'schools' 'scholastic' ' instruction' verb verb verb n o u n noun n o u n noun n o u n adj-like noun Figure 1: Some stems built on root d r s ized multiple times in a surface string. Semitic morphology, including stem interdigitation and spreading, is adequately and elegantly formalizable using finite-state rules and operations. 1.1 A r a b i c S t e m s The stems in Figure 12 share the d r s root morpheme, and indeed they are traditionally organized under a d r s heading in printed lexicons like the authoritative Dictionary of Modern Written Arabic of Hans Wehr (1979). A root morpheme like d r s interdigitates with a pattern morpheme, or, in some analyses. with a pat tern and a separate vocalization morpheme, to form abstract stems. Because interdigitation involves pat tern elements being inserted between the radicals of the root morpheme, Semitic stem formation is a classic example of non-concatenative morphotactics. Separating and identifying the component morphemes of words is of course the core task of morphological analysis for any language, and analyzing Semitic stems is a classic challenge 2The taa~ marbuu.ta, notated here as ( t ) , is the feminine ending pronounced only in certain environments. Long consonants and long vowels are indicated here with gemination.