An Axiomatization of Choquet Expected Utility with Cominimum Independence

This paper proposes a class of independence axioms for simple acts. By introducing the E-cominimum independence axiom that is stronger than the comonotonic independence axiom but weaker than the independence axiom, we provide a new axiomatization theorem of simple acts within the framework of Choquet Expected Utility. Furthermore, in order to provide the axiomatization of simple acts, we generalize Kajii, Kojima, and Ui (2007, Journal of Mathematical Economics) into an infinite state space. Our axiomatization theorem relates Choquet Expected Utility to Multi-prior Expected Utility through the core of a capacity that is explicitly derived within our framework. Our result in this paper also derives Gilboa (1989, Econometrica), Eichberger and Kelsey (1999, Theory and Decision), and Rohde (2010, Social Choice and Welfare) as a corollary.