Automatic Identification of Support Verbs: A Step Towards a Definition of Semantic Weight

Current measures of the readability of texts are very simplistic, typically based on counts of words or syllables per sentence. A more sophisticated analysis needs to take account of the fact that the particular distributions of meanings across wordings chosen by the writer, and the consequent variations in syntactic structure, have a significant effect on readability. A step towards the required sophistication is provided by the notion of lexical density (Halliday, 1985), which suggests that different words carry different amounts of semantic weight; this idea of semantic weight is also used implicitly in areas such as information retrieval and authorship attribution. Current definitions of these notions of lexical density and semantic weight are based on the division of words into closed and open classes, and on intuition. This paper develops a computationally tractable definition of semantic weight, concentrating on what it means for a word to be semantically light; the definition involves looking at the frequency of a word in particular syntactic constructions which are indicative of lightness. Verbs such as make and take, when they function as support verbs, are often considered to be semantically light. To test our definition, we carried out an experiment based on that of Grefenstette and Teufel (1995), where we automatically identify light instances of these words in a corpus; this was done by incorporating our frequency-related definition of semantic weight into a statistical approach similar to that of Grefenstette and Teufel. The results show that this is a plausible definition of semantic lightness for verbs, which can possibly be extended to defining semantic lightness for other classes of words. ∗Reprinted with kind permission from: ”Automatic Identification of Support Verbs: A Step Towards a Definition of Semantic Weight” in Proceedings of the Eighth Australian Joint Conference on Artificial Intelligence (World Scientific, Singapore, 1995) pp 451 458. Copyright by World Scientific Publishing Co. Pte, 1995.