Computing a common prior

Abstract

Morris (1994) and Feinberg (2000) showed that a finite type space admits a common prior if and only if there is no agreeable bet in it.We also consider finite type spaces and observe that the problem of computing a common prior is equivalent to considering the intersection of affine spaces spanned by the types of a player. Therefore, we can apply the Fredholm alternative and conclude that the computational complexity of computing a common prior is strongly polynomial.