Case Based Representation and Retrieval with Time Dependent Features

Abstract. The temporal dimension of the knowledge embedded in cases has often been neglected or oversimplified in Case Based Reasoning sys-tems. However, in several real world problems a case should capture the evolution of the observed phenomenon over time. To this end, we propose to represent temporal information at two levels: (1) at the case level, if some features describe parameters varying within a period of time (which corresponds to the case duration), and are therefore collected in the form of time series; (2) at the history level, if the evolution of the system can be reconstructed by retrieving temporally related cases. In this paper, we describe a framework for case representation and retrieval able to take into account the temporal dimension, and meant to be used in any time dependent domain. In particular, to support case retrieval, we provide an analysis of similarity-based time series retrieval techniques; to support history retrieval, we introduce possible ways to summarize the case content, together with the corresponding strategies for identifying similar instances in the knowledge base. A concrete ap-plication of our framework is represented by the system RHENE, which is briefly sketched here, and extensively described in [20].

Broadway: A Case-Based System for Cooperative Information Browsing on the World-Wide-Web.

: The World Wide Web is a huge hypermedia where finding relevant documents is not an easy task. In this paper, we present our case-based system for cooperative information browsing, called BROADWAY. BROADWAY follows a group of users during their navigations on the WWW (proxy-based architecture) and advise them by displaying a list of potentially relevant documents to visit next. BROADWAY uses case-based reasoning to reuse precise experiences derived from past navigations with a time-extended situation assessment: the advice are based mainly on similarity of ordered sequence of past accessed documents. In addition, the dynamic of the WWW is addressed in the reuse step and with a specific method for case forgetting. 1. Introduction The World Wide Web (WWW) [15] is an hypermedia of heterogeneous and dynamic documents. This virtual space is growing more and more every day, offering to the user a huge amount of data [4]. Two kinds of methods can be used to locate a relevant document throu..