Browsing by Author "Hying, Christian"

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    A clustering approach to automatic verb classification incorporating selectional preferences: model, implementation, and user manual
    (2010) Schulte im Walde, Sabine; Schmid, Helmut; Wagner, Wiebke; Hying, Christian; Scheible, Christian
    This report presents two variations of an innovative, complex approach to semantic verb classes that relies on selectional preferences as verb properties. The underlying linguistic assumption for this verb class model is that verbs which agree on their selectional preferences belong to a common semantic class. The model is implemented as a soft-clustering approach, in order to capture the polysemy of the verbs. The training procedure uses the Expectation-Maximisation (EM) algorithm (Baum, 1972) to iteratively improve the probabilistic parameters of the model, and applies the Minimum Description Length (MDL) principle (Rissanen, 1978) to induce WordNet-based selectional preferences for arguments within subcategorisation frames. One variation of the MDL principle replicates a standard MDL approach by Li and Abe (1998), the other variation presents an improved pruning strategy that outperforms the standard implementation considerably. Our model is potentially useful for lexical induction (e.g., verb senses, subcategorisation and selectional preferences, collocations, and verb alternations), and for NLP applications in sparse data situations. We demonstrate the usefulness of the model by a standard evaluation (pseudo-word disambiguation), and three applications (selectional preference induction, verb sense disambiguation, and semi-supervised sense labelling).
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    Semantics of projective locative expressions : an empirical evaluation of geometrical conditions
    (2009) Hying, Christian; Kamp, Hans (Prof. Dr. h.c., Ph.D.)
    This thesis presents a method for evaluating semantic theories of projective locative expressions such as "X is above Y" and "X to the right of Y". The method is implemented for semantic theories that represent meaning of projective locative expressions in terms of geometrical constraints in two-dimensional space. A set of semantic theories is defined according to proposals from the literature. These theories predict precise geometrical constraints for projective locative expressions. Furthermore, a formalism is proposed which is used to combine these theories in order to generate new semantic theories that are capable of handling vagueness of projective locative expressions. The empirical basis of the evaluation is a set of expressions that subjects of a "map task" experiment (Anderson et al., 1991) have used to describe spatial relations in two-dimensional space. Each expression refers to a specific map of which two-dimensional geometrical representations are derived. The semantic theories are tested with these data by checking whether the geometrical constraints predicted for an expression are satisfied by the corresponding geometrical representation. The evaluations show good results for most theories which have been proposed in the literature. The results are systematically improved by the corresponding theories that handle vagueness.