最適性理論 (Optimality Theory; ot) について，「#3848. ランキングの理論 "Optimality Theory"」 ([2019-11-09-1])，「#3867. Optimality Theory --- 話し手と聞き手のニーズを考慮に入れた音韻理論」 ([2019-11-28-1])，「#1581. Optimality Theory の「説明力」」 ([2013-08-25-1]) で簡単に紹介してきたが，私自身がこの理論に詳しいわけではまったくない．実際，OT の独特な記法であるランキング表の読み方もおぼつかないので，Carr and Montreuil (259) に依拠して，読み方を勉強してみた．
The most common faithfulness constraints are I-O, i.e. they evaluate the matching between input and output. Any candidate which does not diverge from the input is considered the faithful candidate. Any candidate which diverges from the input in order to satisfy some markedness constraint (M) violates some faithfulness constraint (F).
The prototype situation runs like this. If /a/ is the input, but surfaces as [b] because [b] is easier to pronounce than [a], then there is some markedness constraint of the type *a (= avoid [a]). The faithful candidate is [a], but it is defeated by constraint *a, leaving [b] as the winning candidate. While [b] is unfaithful to /a/, and violates a faithfulness constraint IDENT-a, it still wins in a grammar where markedness dominates faithfulness (M >> F). Informally, IDENT-a says: 'do not change the features of /a/'. Constraints are universal, so both *a and IDENT-a will be found in all grammars, but a language where /a/ is realized as [a] will have the same two constraints in the opposite order: F >> M.
Tableaus read from left to right, with the dominating constraints on the left. Violations are indicated by an asterisk. Exclamation marks indicate fatal violations and the cells to the right are shaded to indicate that the information they contain does not play a role in the evaluation, i.e. the decision has been made on the basis of the information contained in the white cells. The hand ☞ indicates the optimal candidate, the winner. It is clear to see that in an F >> M scenario, the faithful candidate is selected as the winner . . . .
|Input /a/||Markedness: *a||Faithfulness: IDENT-a|
|☞ (optimal) [b]||*|
|Input /a/||Faithfulness: IDENT-a||Markedness: *a|
|☞ (faithful and optimal) [a]||*|
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