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On expected and von Neumann-Morgenstern utility functions

2010

Abstract

In this note we analyze the relationship between the properties of von Neumann-Morgenstern utility functions and expected utility functions. More precisely, we investigate which of the regularity and concavity assumptions usually imposed on the latter transfer to the former and vice versa. In particular we obtain that, in order for the expected utility functions to fulfill such classical properties, it

Key takeaways

  • Household's preferences are represented by a utility function U : R G ++ → R. According to [1] that utility function is named "expected utility function" when it has the following form
  • Then U satisfies (2)-(5) if and only if u fulfills (6)-(9).
  • Vice versa, let us assume that U : R G ++ → R in (1) fulfills (4) and let us show that u : R 2C ++ → R satisfies (8).
  • Let us now assume that the continuous and lower unbounded function u : R 2C ++ → R satisfies (9) and we prove that U in (1) fulfills (5).
  • We notice that an argument similar to the one used in the proof of Theorem 1 to check that (4)⇒(8) also shows that if U : R G ++ → R in (1) satisfies (23) then u : R 2C ++ → R fulfills (24).