Affiliation: | Faculty of Mathematics, University of Waterloo, Waterloo, Ontario, Canada ~N2L 3G1 ; Institute of Mathematics, Silesian University, Bankowa 14, PL-40-007 Katowice, Poland ; Universität GH Paderborn, FB 17, D-33095 Paderborn, Germany |
Abstract: | The problem of determining all utility measures over binary gambles that are both separable and additive leads to the functional equation The following conditions are more or less natural to the problem: strictly increasing, strictly decreasing; both map their domains onto intervals ( onto a , onto ); thus both are continuous, , , , , . We determine, however, the general solution without any of these conditions (except , , both into). If we exclude two trivial solutions, then we get as general solution (, ; for ), which satisfies all the above conditions. The paper concludes with a remark on the case where the equation is satisfied only almost everywhere. |