  In Turkish, (and possibly in many other languages) verbs often convey several
meanings (some totally unrelated) when they are used with subjects, objects,
oblique objects, adverbial adjuncts, with certain lexical, morphological, and
semantic features, and co-occurrence restrictions. In addition to the usual
sense variations due to selectional restrictions on verbal arguments, in most
cases, the meaning conveyed by a case frame is idiomatic and not compositional,
with subtle constraints. In this paper, we present an approach to building a
constraint-based case frame lexicon for use in natural language processing in
Turkish, whose prototype we have implemented under the TFS system developed at
Univ. of Stuttgart.
  A number of observations that we have made on Turkish have indicated that we
need something beyond the traditional transitive and intransitive distinction,
and utilize a framework where verb valence is considered as the obligatory
co-existence of an arbitrary subset of possible arguments along with the
obligatory exclusion of certain others, relative to a verb sense. Additional
morphological lexical and semantic constraints on the syntactic constituents
organized as a 5-tier constraint hierarchy, are utilized to map a given
syntactic structure case-fraame to a specific verb sense.
