Optimal register variation

In siSwati (Guthrie S.43), [+hi] vowels are elided interconsonantally during fast speech. Interconsonantal [+hi] vowel elision takes place under four conditions: 1) the vowel occurs in a non-prominent syllable, 2) the vowel occurs in a functional morpheme, 3) the front [+hi] vowel [i] precedes or follows [s], 4) the back [+hi] vowel [u] follows [k]. This paper presents an Optimality Theoretic analysis of this pattern of [+hi] vowel elision which includes partial constraint rankings with opposite rankings of relevant constraints for elision and non-elision environments and constraints to restrict elision to non-prominent functional morphemes by favouring the parsing of vowels in complementary environments. Restrictions on consonants adjacent to elided vowels are accounted for in terms of the greater faithfulness of elision when the elided vowel and its adjacent consonant share features whose parsing is highly preferred.