Contextual weighted representations and indexing models for the retrieval of HTML documents

Abstract

The diffusion of the World Wide Web (WWW) and the consequent increase in the production and exchange of textual information demand the development of effective information retrieval systems. The HyperText Markup Language (HTML) constitues a common basis for generating documents over the internet and the intranets. By means of the HTML the author is allowed to organize the text into subparts delimited by special tags; these subparts are then visualized by the HTML browser in distinct ways, i.e. with distinct typographical formats. In this paper a model for indexing HTML documents is proposed which exploits the role of tags in encoding the importance of their delimited text. Central to our model is a method to compute the significance degree of a term in a document by weighting the term instances according to the tags in which they occur. The indexing model proposed is based on a contextual weighted representation of the document under consideration, by means of which a set of (normalized) numerical weights is assigned to the various tags containing the text. The weighted representation is contextual in the sense that the set of numerical weights assigned to the various tags and the respective text depend (other than on the tags themselves) on the particular document considered. By means of the contextual weighted representation our indexing model reflects not only the general syntactic structure of the HTML language but also the information conveyed by the particular way in which the author instantiates that general structure in the document under consideration. We discuss two different forms of contextual weighting: the first is based on a linear weighted representation and is closer to the standard model of universal (i.e. non contextual) weighting; the second is based on a more complex non linear weighted representation and has a number of novel and interesting features.