Surface constraints on multiple occurrences of the tense expletive

The current paper proposes a constraint-based syntax-optimality-theoretic (CBS-OT) alternative to the conventional assumption or to a plausible phonological analysis of the `non-past' tense morpheme and the verbal base forms, which performs a division of labor among linguistic components. The analysis of the so-called `non-past' morpheme as the default morpheme of tense, or the tense expletive, is the key of the proposal. 1. The conventional assumption and a plausible phonological analysis and their inadequacy: If the conventional assumption for the strong base verbs in standard Japanese, as assumed in, for example, Hayata (1998:32), were extended to Yamaguchi dialect, we would end up with stipulating that each of the `/n/ consonantnal base' verbs (/sin/ `die' and /in/ `leave' only) has another base form with the vowel /u/ added to the end of the usual one in the dialect. This is because the verbs use the longer `base forms' in the `non-past' and /(r)eba/-conditional forms, as in, for example, (1a-i), similarly to the cases of the strong base verbs (e.g., (1b-i)). And yet, they use the shorter base forms in the negative, present participle and passive forms, as in, for example, (1a-ii), similarly to the cases of the standard strong base verbs (e.g., (1b-ii)). The `non-past' and /(r)eba/conditional forms of the /n/ consonantnal base verbs in Yamaguchi dialect and those in standard are distinct, as in, for example, between (1a-i) and (1c-i) in contrast with an identity in the other verb forms, for example, between (1a-ii) and (1c-ii).