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106 constraint demotion algorithm
Later generative studies aimed to find constraints which apply to large classes
of derivations (i.e. the constraints have a greater explanatory power) – a trend
which contrasts with the local application of the constraints proposed in the
1960s. ‘Constraints’, in this work, are distinguished from ‘filters’: the former are
conditions affecting two successive phrase-markers in a derivation: the latter are
conditions on a single level of structure, which serves as the output of a given set
of rules.
The notion of constraints takes a different direction in optimality theory,
where it is the principal explanatory device (abbreviated as CON). Here,
constraints are ways of characterizing language universals. Each language
has its own ranking of constraints (e.g. which determine morpheme position
or syllable structure), and differences between these rankings result in the
variations observed between languages. Constraints are found only in the constraint
hierarchy for a language, i.e. the language’s particular ranking of the
universal set of constraints; there are no separate constraints operating on
inputs or outputs, and no rules to be constrained. The approach also uses the
notion of constraint satisfaction, representing the extent to which a constraint
can be violated in grammatical forms. All constraints are violable. The output
forms are the optimal ones (i.e. with the minimum number of constraint
violations), selected by the evaluator component of the theory. The term
is also used more generally in generative linguistics with reference to theory
construction. A linguistic theory needs to be constrained, in order to restrict
the class of potential grammars. In this sense, the main aim of linguistics is said
to be the provision of an explanatorily adequate theory which is maximally
constrained.
constraint demotion algorithm A theory of the acquisition of an optimality
theory grammar. All constraints are initially ranked together, and as new
forms are encountered, constraints that show violations in the forms in the
data are progressively lowered in the ranking. A modification is called the biased
constraint demotion algorithm, which starts with a ranking of all markedness
constraints over all faithfulness constraints.
constriction (n.) A general term used in articulatory phonetics to refer to
a narrowing within the vocal tract. The different kinds and degrees of constriction
are the basis of the articulatory classification of sound qualities. The
term constricted is sometimes used in a restricted sense, referring to glottalized
sounds or the glottis with narrow aperture (opposed to spread). ‘Constriction’
has developed a central role in phonological theory, especially in some
models of feature geometry. A constriction model aims to unify the description
of vocoids (vowels and glides) and consonants in terms of their characteristic
constriction, defined by the parameters of constriction degree (a continuant
node for consonants and an aperture node for vocoids) and constriction location
(a place node, represented by ‘C-place’ for consonants and ‘V-place’ for
vocoids, and defined in terms of the active articulator involved). Constrictions
are represented by a separate node in the feature hierarchy, and degree and
location are separate nodes linked under the constriction node. The definition of
dorsal, for example (involving a constriction formed by the back of the tongue)
is equally applicable to consonants and vocoids, thus avoiding the ‘two-mouth’