Eckhard Bick - VISL

2.2.5.1), without ultimately losing the syntactic or semantic information 251 residing
in traditional word class definitions (like the categories of demonstrative, possessive,
indefinite, interrogative and relative pronouns, for what I have morphologically
defined as determiners [DET, number/gender-inflecting] and independent specifiers
[SPEC, non-inflecting]). Likewise, sense-distinctions alone were not regarded as a
sufficient criterion for lexeme-distinctness, reserving, for instance, the distinction of
the etymologically unrelated, but in Brazilian Portuguese homographic, ‘fato’ and
‘fa(c)to’ for the semantic level - to be performed by sense tag disambiguation. This
way, a purely morphological approach to lexeme identity was possible.
One of the main objectives of this dissertation has been to show that the
Constraint Grammar approach, which from the beginning has stressed the
importance of a parsing lexicon and grown from morphology into syntax (Karlsson,
1995, p.11), is ideally suited for such progression, not alone towards more “delicate”
syntax, but also with respect to notational filtering (constituent or dependency trees)
and, ultimately, semantics and semantics-based applications (like MT), - provided
the lexicon is upgraded along the way. It appears justified to say that the progression
on the syntactic level, involving subclause function, clause level dependency
markers and constituent tree transformation, has yielded quantifiable results
comparable to what has been achieved for the “benchmark” surface syntax of
ENGCG (cp. chapters 3.9 and 8.1).
Though here I have only sketched the outlines of a semantic CG-level (in
chapters 5 and 6), a working system has been implemented for the entire lexicon,
and disambiguation rules have been written for comprehensive valency instantiation,
as well as selected areas of polysemy resolution, showing that - at least in principle -
Constraint Grammar can be used to address parsing tasks at these levels. Valency
instantiation, though it could be performed in many other ways, shows how the CG
formalism can be made to handle what basically is a unification process, exploiting
unambiguous syntactic information that has already been established (tagged).
Unlike ordinary disambiguation rules, most of the valency unification rules are
relatively simple, REMOVE rules often involving only the target valency tag and
two unbounded context conditions, one left, one right, checking for the presence of a
matching argument 252 . On the other hand, rules targeting semantic features or
semantic prototype tags cannot be based on established syntactic tags alone, but need
to take into account other (semantic) ambiguous information, resulting in a rule type
more reminiscent of the morphological and syntactic levels. Finally, there is ongoing
work involving a translation-equivalent Constraint Grammar for Portuguese-Danish
machine translation, which is basically a context conditioned mapping grammar,
refining and correcting the translations obtained by using morphological, syntactic,
valency- and semantic tags as polysemy discriminators. And though such a statement
should be worded carefully, nothing indicates insurmountable difficulties on the
immediate Constraint Grammar application horizon ...
251 This information, no not morphologically explicit, is retained by means of secondary and function tags, which can be
exploited to recreate the traditional pronoun classes in a given application.
252 For instance: REMOVE () (NOT *1 @