Case base maintenance is one of the most important issues for current research in Case-Based Reasoning (CBR). In this paper, we outline two novel steps as part of the maintenance phase of the CBR process. The review step covers assessment and monitoring of the knowledge containers whereas the restore step actually modifies the contents of the containers according to recommendations resulting from the review step. Here, we focus our attention on the review step for the case base. For this purpose, we define several quality measures based on different case and case base properties that describe specific characteristics of the case base such as correctness, consistency, uniqueness, minimality, and incoherence. These measures allow an initial implementation of the review step for the case base container. We conclude the paper with an outline of future work to extend these aspects of maintenance in CBR.

Case-base maintenance is one of the most important issues for current research in case-based reasoning (CBR). In this article we propose an extended six-step CBR cycle and discuss its two additional steps as part of the maintenance phase of the CBR process. The review step covers assessment and monitoring of the knowledge containers, whereas the restore step actually modifies the contents of the containers according to recommendations resulting from the review step in order to keep the knowledge containers in a usable state. Here we focus our attention on the case base. For the review step, we define several quality measures based on different case and case-base properties that describe specific characteristics of the case base such as correctness, consistency, uniqueness, minimality, and incoherence. Then we use these measures to realize monitoring capabilities for the case-base container that indicate when the restore step is necessary. Finally, we also describe several methods for modifications of the case base in the restore step and their relation to the review step. An initial experimental evaluation shows the appropriateness of the proposed concepts and methods before we conclude the article with a discussion of related work and an outline of future directions to extend these aspects of maintenance in CBR.

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Maintenance of Case-Based Reasoning (CBR) systems became an important area since applications of CBR technologies were established in different real-world domains. Maintenance issues cover all aspects that help to keep a running CBR system in a usable state of high quality. Concepts and techniques that were developed for maintenance of CBR systems range from methodologies and frameworks that particularly define phases, steps, and tasks necessary to integrate maintenance into the CBR process up to specific programs that enable CBR engineers to carry out the maintenance activities. In this paper, we exemplify this range of research on maintenance of CBR systems by brief characterizations of the SIAM methodology, the MAMA maintenance manual, and the MASH maintenance shell. The overall goal of this paper is then to conclude areas for further research in maintenance for CBR systems from the experience of the work on SIAM, MAMA, MASH, and related approaches.