Eckhard Bick - VISL

3.7 Contextual information in constraint building
3.7.1 Implicit syntax: Exploiting linear structure
A Constraint Grammar has at its disposal three types of information, of which the
morphological level usually 114 only exploits two (a/b):
(a) lexical information, part disambiguated or being disambiguated (base form,
word class and inflexion tags), part not (secondary valency and semantic tags)
(b) the linear order of words and non-words (punctuation symbols, numbers) in a
sentence.
(c) At the syntactic level, in addition, non-lexical information (syntactic function
and dependency tags) is made “lexical” (mapped onto word forms) and disambiguated
creating a third type of information to be used by the CG rules.
What a CG rule does, is - in principal - stating whether a certain sequence of
word based tags is grammatical or not. The actual compiled grammar is handed
(partially ambiguous) information of type (a) and (b) from the morphological analyser
(or its own mapping module), and then extracts information of type (b) from a given
sentence, trying to instantiate one or more matching tag sequences from the rule body.
Since they basically express word/tag sequences, all CG rules could be called
syntagmatic, - even the morphological ones. For example, a CG grammar does not state
agreement rules per se, and does not operate with the concept “noun group” (np) as
such. Still, both syntactic concepts are implicitely employed even on the morphological
level. Consider the following tag sequences (DET = determiner, N = noun, A =
adjective, V = verb, M = masculine, F = feminine, S = singular, P = plural, 3 = third
person, *agrammatical):
... DET-MS NMS AMS V3S ...
... DET-FS NFS AFS V3S ...
... DET-MP NMP AMP V3P ...
... DET-FP NFP AFP V3P ...
... DET-M *NF AM V3 ...
... DET-F *NM AF V3 ...
... DET-S *NP AS V3S ...
... DET-P *NS AP V3P ...
114 That is, if the morphological and syntactic levels are kept apart in a strict way, not least for linguistic reasons.
Technically, a CG-grammarian can choose - rather than apply too heuristic rules at the morphological level proper - to run
an additional round of morphological rules after the syntactic mapping and disambiguation phases, in order to address the
remaining “hard” morphological ambiguity with more (i.e. syntactic) context information.
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