Four-Valued Knowledge Augmentation for Representing Structured Documents

Structured documents are composed of objects with a content and a logical structure. The e ective retrieval of structured documents requires models that provide for a content-based retrieval of objects that takes into account their logical structure, so that the relevance of an object is not solely based on its content, but also on the logical structure among objects. This paper proposes a formal model for representing structured documents where the content of an object is viewed as the knowledge contained in that object, and the logical structure among objects is capture by a process of knowledge augmentation: the knowledge contained in an object is augmented with that of its structurally related objects. The knowledge augmentation process takes into account the fact that knowledge can be incomplete and become inconsistent. The model is based on the de nitions of four truth values, modal operators, possible worlds, accessibility relations and truth value assignments used to characterise content knowledge, structural knowledge, augmented knowledge, incompleteness and inconsistency.