Predicate-Argument Structure

260 Toni Badia, Carme Colominas
a setting that the abstract representations of sentences in the different languages considered are
as much similar as possible. If we think of applications in which a module is introduced that
is independent from language (information retrieval, interface to data bases...) the more similar
are the representations from different languages the better since the link between the linguistic
modules and the external one is going to be much simpler (there will not be major differences for
the different languages).
On the other hand, the fully semantic representation is problematic in that there is no general
approach that can be applied to a large range of linguistic phenomena. There are of course
proposals to use thematic roles to characterise the relations that the predicates have with their
arguments; there is quite a large litterature on cases, semantic roles or thematic roles. However
there is no general treatment of such abstract relations that is both general enough to deal with all
major complementation patterns in languages and consistent with an overall semantic perspective.
A characterisation of the predicate-argument relations that is both strongly dependent on syntactic
structure and abstract enough to overcome the major differences between equivalent surface
structures of sentences in the different languages can be obtained from the efforts mentioned
above about the definition of a transfer interface for MT.
Given the basic assumptions of this project (see chapter 2 (Formal Assumptions)), any such theory
needs to be adapted to a TFS format, in a way that is consistent with the basic principles of a lean
version of HPSG. There are two dimensions upon which this conversion has to be performed:
the labelling of predicative types and arguments, and the basic structure of the content types in
general. These are indeed two aspects of HPSG which raise problems when trying to widen the
coverage of the grammar.
In standard HPSG there is no consistent labelling of predication types nor of argument classes.
Instead the relation represented by a predicate is used as the label of the type (actually, a subtype
of the type qfpsoa) and arguments are labelled with relation-related tags (e.g., liker and liked for
the relation type like). Indeed such a treatment is not adequate to express generalisations about
the predicate-arguments structure.
On the other hand, there is no treatment of modifiers to predications in standard HPSG. Although
the proposal for modifiers to nominal objects conforms to the standard approaches to modifiers
in semantically oriented theories, the application of this proposal to predicative signs is not
straightforward. Indeed the same problems occur that are found in any logical form treatment of
modifiers to predication.
These two aspects then have to be restated in our TFS lean formalism, since there are no clear
proposals for them in HPSG proper. To these two question we turn our attention in the next two
sections.
6.2.2 THE BASIC STRUCTURE OF THE CONTENT OF SIGNS
There are two fundamental problems concerning the generalisation of the structure of the type
content to a large range of phenomena. These are the representation of the PAS of nominals and
the integration of adjuncts to predicates with their PAS. Let us start by considering the problem
of the representation of adjuncts to predicative signs.
The fact that adjuncts to predicative signs do not fit in the content type of predicative signs
basically derives from the lack of an index to which adjuncts could impose restrictions.