Subject-Keyphrase Extraction Based on Definition-Use Chain

In this paper, we propose a new concept called subject-keyphrase and also introduce a method to extract subject-keyphrases from a document. Subject-keyphrases refer to the words or phrases used to represent the sentence subjects of a document, i.e., the content of a document is organized around the subjects of the document. It can be expected that each sentence of a document is composed of a subject and an object, where the subject is defined in relation to its object. Using "definition" and "use" relations, we may thus identify the subjects in a given document by looking for keyphrases which appear frequently as subjects of sentences in the document. We thus present a subject-keyphrase extraction (SKE) algorithm based on the notion of definition-use chain (DU Chain) to identify subject-keyphrases. Experimental results show that SKE can successfully identify the subject-keyphrases to effectively capture the main idea of a document.