A Note on Common Prior

Abstract

Harsányi introduced the concept of type space in an intuitive way. Later Heifetz and Samet formalized it. Harsányi used conditional probabilities to model the beliefs of the players, Heifetz and Samet avoided using conditional probabilities formally. We show that in both cases the concept of transition probability can reproduce the models, moreover, the transition probability approach fits to both Harsányi's intuition and the formalization of Heifetz and Samet. As a consequence, our results suggest that the concept of common prior is not appropriate to determine the players' beliefs. Two examples are also given.Beliefs, Conditional probability, Common Prior