Resumen de Continuous representations of effectivity functions
An effectivity function specifies for each coalition a collection of subsets of alternatives such that the coalition can force society�s choice to belong to this subset. Effectivity functions have found widespread application in implementation theory; much recent research is concerned with the so-called representation problem of finding a game form having a prescribed effectivity function.
In the general setting where the set of alternatives is compact metric space, the problem of finding a continous representation (a representing game form with continuous outcome function) is highly non-trivial. In the present paper we give a new characterization of continuously representable effectivity functions using a property of continuous (not necessarily single valued) selections of certain operations on the subsets selected by the effectivity function.
