Alternatives Organizer in Group Decision Making: An Ontology Approach Bakhta Nachet, Abdelkader Adla, Mohammed Frendi Department of Computer Science, University of Oran 1 Ahmed Ben Bella {nachetdal, mohamedfrendi}@yahoo.fr adla.abdelkader@univ-oran.dz Abstract: Group Decision Support Systems (GDSS) provide a means by which a larger number of organizational decision makers, may be in different locations, can efficiently and effectively participate in the group decision making process. In the latter, the alternatives amongst which a decision must be made can range from a few to a few thousand. The facilitator (or the decision makers) need(s) to narrow the possibilities down to a reasonable number, and categorize and classify alternatives, especially where the alternatives can be put into numerical terms. Even when this is not the case, facilitation support, such as ontology-based frameworks potentially offer these capabilities and can assist the decision-maker in presenting the alternatives in a form that facilitates the decision. Because of the problems, frustrations, and great amount of time experienced in alternatives organization, we introduce an ontology based approach and a software tool that supports the facilitator in addressing the process problem of cognitive load associated with alternatives organizing stage by synthesizing and organizing group alternatives. The resulting alternatives organizing tool is based on ontologies built using the Web Ontology Language (OWL) which facilitates the sharing and integration of decision-making information between multiple decision makers. Keywords: GDSS, Ontology, Concept Categorization, Group Facilitation, OWL 1. Introduction The need for Group Decision Making (GDM) techniques and support is greater than ever before. This is due to the complexity of business relationships, the greater number of decision makers and organizations that are involved in the decision process, online access to multiple external information sources, and the decreasing in the time allowed for decision making. In the group decision making process, the alternatives amongst which a decision must be made can range from a few to a few thousand [1][2]. The facilitator (or the decision makers) need(s) to narrow the possibilities down to a reasonable number, and categorize and classify alternatives, especially where the alternatives can be put into numerical terms. Even when this is not the case, facilitation support, such as ontology-based frameworks potentially offer these capabilities and can assist the decision-maker in presenting the alternatives in a form that facilitates the decision. In this research, an ontology based approach is developed to facilitate organizing alternatives during the group decision making process. The alternatives organizing tool is based on two ontologies: application-domain ontology and domain ontology. The first ontology will allow structuring all documented possible decisions by specifying semantic inter-relations. The domain ontology defines the objects of the domain as well as their inter-relations. This second ontology will ensure another aspect of the generalization link between decisions. As a result, these two ontologies are supplementary and each one ensures an aspect of the decision organizing. We have built the ontologies using the Web Ontology Language (OWL) which facilitates the sharing and integration of decision-making information between multiple decision makers via the Web and Description Logic. The remainder of this article is structured as follows: a background on group decision making and decision support is given in section 2. The section 3 presents related works. In the section 4, we develop our ontology-based approach to organize alternatives decision in the group decision making process. Section 5 is devoted to a detailed presentation of the developed ontologies to facilitate the alternatives organizing, followed par an illustration with an example in section 6. Finally, in section 7 we conclude and give future work. 2. Related Work Decision aid and decision making have greatly changed with the emergence of information and communication technology (ICT). Decision makers are now far less statically located; on the contrary they play the role in a distributed way. This fundamental methodological change creates a new set of requirements: distributed group decision making is necessarily based on incomplete data, it must be possible at any moment, and it might be necessary to interrupt a decision process and to provide another, more viable decision. “Distributed