112 research outputs found
Approximate text generation from non-hierarchical representations in a declarative framework
This thesis is on Natural Language Generation. It describes a linguistic realisation
system that translates the semantic information encoded in a conceptual graph into an
English language sentence. The use of a non-hierarchically structured semantic representation (conceptual graphs) and an approximate matching between semantic structures allows us to investigate a more general version of the sentence generation problem
where one is not pre-committed to a choice of the syntactically prominent elements in
the initial semantics. We show clearly how the semantic structure is declaratively related to linguistically motivated syntactic representation â we use D-Tree Grammars
which stem from work on Tree-Adjoining Grammars. The declarative specification of
the mapping between semantics and syntax allows for different processing strategies
to be exploited. A number of generation strategies have been considered: a pure topdown strategy and a chart-based generation technique which allows partially successful
computations to be reused in other branches of the search space. Having a generator
with increased paraphrasing power as a consequence of using non-hierarchical input
and approximate matching raises the issue whether certain 'better' paraphrases can be
generated before others. We investigate preference-based processing in the context of
generation
Transforming data by calculation
Thispaperaddressesthefoundationsofdata-modeltransformation.A catalog of data mappings is presented which includes abstraction and representa- tion relations and associated constraints. These are justified in an algebraic style via the pointfree-transform, a technique whereby predicates are lifted to binary relation terms (of the algebra of programming) in a two-level style encompassing both data and operations. This approach to data calculation, which also includes transformation of recursive data models into âflatâ database schemes, is offered as alternative to standard database design from abstract models. The calculus is also used to establish a link between the proposed transformational style and bidi- rectional lenses developed in the context of the classical view-update problem.Fundação para a CiĂȘncia e a Tecnologia (FCT
Graph Theory and Universal Grammar
Tese arquivada ao abrigo da Portaria nÂș 227/2017 de 25 de Julho-Registo de Grau EstrangeiroIn the last few years, Noam Chomsky (1994; 1995; 2000; 2001) has gone quite far in
the direction of simplifying syntax, including eliminating X-bar theory and the levels
of D-structure and S-structure entirely, as well as reducing movement rules to a
combination of the more primitive operations of Copy and Merge. What remain in
the Minimalist Program are the operations Merge and Agree and the levels of LF
(Logical Form) and PF (Phonological form).
My doctoral thesis attempts to offer an economical theory of syntactic structure
from a graph-theoretic point of view (cf. Diestel, 2005), with special emphases on the
elimination of category and projection labels and the Inclusiveness Condition
(Chomsky 1994). The major influences for the development of such a theory have
been Chris Collinsâ (2002) seminal paper âEliminating labelsâ, John Bowers (2001)
unpublished manuscript âSyntactic Relationsâ and the Cartographic Paradigm (see
Belletti, Cinque and Rizziâs volumes on OUP for a starting point regarding this
paradigm).
A syntactic structure will be regarded here as a graph consisting of the set of
lexical items, the set of relations among them and nothing more
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