Abstract
This paper describes a computer system supporting negotiations in group decision to seek a solution, where consensus is incomplete, by carring out an encounter-type simulation. The system is based on the utility theory including utility functions which are modified according to the status given by the values and coefficients of utility functions. A consensus is seeked through the modification of the functions. As a concrete example, we demonstrate the use of the system for group car buying decisions. The results can be summarized as follows. (1) A negotiation rule with the concept of utility theory makes it possible to seize negotiators' utility values in quantity which is changeable. And that contributes to clarifying the process of compromise. (2) Those who implement this encounter-type simulation with computer are able to negotiate experimentally and moreover, to give a try to induce a reasonable consensus objectively. (3) Elements and relations in each set or criteria in the system are shown graphically or as relational data in matrix form so that it works as an interface supporting decision making in negotiations by supplying us with figures and tables required instantly in the display.
