The contrastive hierarchy in phonology 2009 Dresher.pdf - CUNY ...

a role in the outcome is *[F], which incorrectly selects (a), the least specified
candidate that preserves the input [+low].
The problem is that constraints of the type MAX [F] require only that an
input specification of [F] must be preserved. They have no jurisdiction over a
feature that is absent from the input. If we consider a contrastive tree such as in
(6.12), we understand that it not only prohibits certain feature combinations, it
also requires some features to be present. MAX constraints do not do this, nor do
the co-occurrence constraints. For while a constraint of the form *[coronal, +low]
prohibits certain combinations of features, it does not require any combinations.
Candidates that lack some or all of the features mentioned in such a constraint
simply evade its effects.
To enforce the presence of required contrastive features we need to add a
third type of constraint, requiring the presence of a feature in the context of other
features. One way is by an implicational constraint of the form in (6.28).
(6.28) Implicational constraint
[Φ] ⊃ [F]: The set of feature specifications [Φ] requires the presence
of feature [F].
When a value of [F] is specified in the input, MAX [F] will ensure it is maintained.
When no value is specified, the implicational rule will penalize any candidate
that lacks [F].
In Classical Manchu, a set of implicational constraints that mirrors the
contrastive tree in (6.12) is given in (6.29).
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