Structural Relations - A Case Against Case

II THE REPRESENTATION Usually semantic parsers of NLU systems rely on some type of 'deep cases' (Riesbeck and Schank, 1976), (Trost and Steinacker, 1981) to control analysis. While we do not want to deny the advantages of such an approach (we use it ourselves), we propose to apply a different approach in order to analyse words that derive their meaning from the semantic category of their dependent constituents. The algorithm we present in this paper disambiguates such words by making use of one of the important properties of an Si-Net (Brachman,1979), the strict distinction between structure and contents of the net. Structurally all semantic relations are represented in the same way therefore we evaluate this level to find out if there is a relation between the representation of the constituents of such a word. After a link has been found its semantic interpretation is taken to be the sense of the word. Besides being used for disambiguation the algorithm is applicable to solve other problems related to parsing as well, e.g. interpretation of metaphors or problems related to resolution of definite anaphora. The structural level of an Si-Net is characterized by the pattern: At the semantic level Concept! describes one of Concept2, the value-restrict range of possible fillers describes the function of the to the concept (Trost and Concepts are part of a super in which a subconcept inherit all superconcepts. an attribute of its properties. ion, indicates the whereas the role filler with regard Steinacker, 1979). subconcept hierarchy, s the attributes of 1 THE PROBLEM HI RELATION BETWEEN VOCABULARY AND SEMANTIC NET In natural languages there exist a number of words that derive their meaning from the semantic category of their dependent constituents. We will call such words relational words. They are used to express an association between their constituents. Examples for relational words are:-possessive pronouns (my job, my sister, my car)-to have (to have a cold, to have a child)-to give (to give a kiss, to give an object)-to get (to get an answer, to get a degree) To interpret such words on the basis of a semantic net there exist two solutions:-to list all different senses of a word explicitly within the dictionary associated with information for disambiguation-to apply a general procedure that relies on a source of knowledge other than the sentence. This paper demonstrates how the structural properties of the Si-Net (Brachman, 1979) can be …