On consistent coalitions in group decision making with flexible decision makers

In this paper we propose a formal framework to deal with situations of grou p decision making with flexible decision makers. In the framework it is ass umed that each decision maker tries to achieve cooperation in a coalition b alancing their flexibility as well as to obtain a consequence as desirable for him/herself as possible. We introduce two different concepts of consist ency of coalitions in order to express the idea of the assumption, and exam ine relations between them. We, moreover, define two types of strategic exc hanges of information about decision makers' opinions, and provide a suffic ient condition to make profitable manipulation of information impossible, i n each case. That is, it is impossible for a decision maker to obtain a pre ferable consequence by strategic information exchange, when the decision ma ker cannot form any new consistent coalitions by the manipulated informatio n, in both cases. (C) 2000 Elsevier Science Inc. All rights reserved.