locality in exceptions and derived environments in vowel harmony

the regular realm of vowel harmony in assamese consists of right-to-left regressive [atr] harmony. in contrast with this regular pattern of vowel harmony, the exceptional assamese processes dealt with in this paper are symptomatic of the behavior of a pair of morphemes that trigger additional processes not seen elsewhere in the language. this pair of morphemes allows raising of the otherwise opaque vowel / open image in new window/ and fronting/backing of / open image in new window/ depending on the [back] quality of a mid vowel adjacent to / open image in new window/. raising is strictly local in the presence of preceding high and low vowels, but there is also another pattern which shows backness assimilation to a previous vowel if there are mid vowels preceding the / open image in new window/ of the input. this exceptional raising occurs to allow [atr] harmony to spread regressively by changing the [−atr] low vowel into a [+atr] mid vowel. i analyse these cases within optimality theory (prince and smolensky 1993/2004) and show that these exceptional occurrences are morpheme-specific. it is also shown that these exceptional occurrences lend themselves to an account based on indexation of markedness constraints (flack 2007; ota 2004; pater 2000, 2006, 2009). consequently, the assamese examples show that indexed markedness constraints are able to deal with an exceptional alternation where a low vowel undergoes harmony locally. this article also shows that an emergence of the unmarked analysis is required to account for the low back vowel that alternates with a front vowel if there is a preceding front vowel. this article goes beyond the problems encountered in assamese, and claims that there is no need to invoke locality in exceptional blocking in vowel harmony, as both exceptional and non-exceptional blocking in vowel harmony are always local and bounded. the goal of this paper is to shed light on exceptional and emergent processes, arguing that they are always local and governed by strong universal properties of grammar.