Consonant Spreading in Arabic Stems

']'his paper examines the phenomenon of consonant spreading in Arabic stems. Each spreading involves a local surface copying of an underlying consonant, and, in certain phonologi~ cal contexts, spreading alternates productively with consonant lengthening (or gemination). The mOrl)hophonemic triggers of spreading lit in the pat terns or even in the roots themselves, and the combination of a spreading root and a spreading pat tern causes a consonant to be coiffed mulliple times. The interdigitation of Arabic stems and the realization of consonant spreading are forlnalized using finite-state roo f photactics and variation rules, and this al> preach 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. deDnd the reality of abstract, unpronounceable morphemes called ROOTS, consisting usually of three, but soinetimes two or four, consonants called RADICALS. The classic examples include k t b (~. CJ '2) 1, al)pearing ill a number of words having to do with writing, books, schools, etc.; and drs (~r' o z), appearing in words having to do with studying, learning, teaching, etc. Roots combine nonconcatenatively with t'ATTI,;flNS to form STt,;MS, a process known informally as INTERDIGITA? 'ION or 1NTBRCALATION. We shall look first at Arabic stems in general before examining GEMINATION and SPREADING, related phenomena wherein a single underlying radical is reall"l'he Arabic-script examples in this paper were produced using the ArabTeX package for ],~GX and DTEX by Prof. I)r. l(laus i, agally of the University of Stuttgart. daras duris dar ras du ruus d i raasa( t ) da r r aa s m ad ra sa ( t ) madaar i s lnadras iyy tadri is 's tudy' 'be studied' ' teach' ' l e s sons ' ' s tudy' 'eager student ' 'school' 'schools' 'scholastic' ' instruction' ve r I) ve rb verb noulI. n o u n Boun no t tn ROllS adj-like sou n Figure 1: Some stems built on root drs ized multiple times in a surface string. Semilic morphology, including stem interdigitation and spreading, is adequately and elegantly fornializable 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 drs root morpheme, and indeed they are traditionally ol:ganized under a d r s heading in printed lexicons like the authori tat ive Dictionary of Alodern Written Arabic of Hans Wehr (197! )). A root morpheme like d r s interdigitales with a pat tern morpheme, or, in some analyses. with a pat tern and a separate vocalization [norpheme, 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 n on-concatenative inorphotactics. 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 ~The taa] ) marbuuta, notated here as (t), is lhe feminine ending pronounced only in certain environments. Long consonants and long vowels are indicated here with gemination.