A new binary relation to compare viability of winning coalitions and its interrelationships to desirability relation and blockability relation

摘要

This paper aims to propose a new type of binary relations, called the viability relation, defined on the set of all coalitions in a simple game for a comparison of coalition influence, and to investigate its properties, especially its interrelationships to the desirability relation and the blockability relation. The viability relation is defined to compare coalitions based on their robustness over deviation of their members for complementing the inability of the desirability relation and the blockability relation to make a distinguishable comparison among winning coalitions. It is verified in this paper that the viability relation on a simple game is always transitive and is complete if and only if the simple game is S-unanimous for a coalition S. Examples show that there are no general inclusion relations among the desirability relation, the blockability relation and the viability relation. It is also verified that the viability relation and the blockability relation are complementary to each other. Specifically, the blockability relation between two coalitions is equivalent to the inversed viability relation between the complements of the two coalitions.