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Some aspects of decision taking under risk are examined. The existence of fair gambles whose price equals their expected values is questioned and in addition the origin of expected utility is analysed.Then a diverse approach to decision taking under risk is considered, whereby agents maximize a utility function of consequences of actions. Consequences are treated like different goods and prospect is like a budle of goods. Stochastic dominance is invoked as a second stage criterion to decide whether to accept or not a prospect. Even though some problems arise as to the continuity by using the indirect utility function we are able to explain the Allais Paradox.

Despite their scarcity in the literature, an abundance of globally regular indirect utility functions, involving as many parameters as desired, exist and are easily constructed as a function of simple homothetic component utilities.

ABSTRACTConcavity and quasiconcavity have always been important properties in financial economics particularly in decision problems when an objective function has to be maximized over a convex set. Both properties have mainly been used as purely technical assumptions. In this paper, we link concavity and quasiconcavity of a utility function to the basic concepts of risk aversion, prudence, risk vulnerability and temperance. We show that concavity means the agent is more risk vulnerable than prudent. In particular, we can see when a function is both concave and quasiconcave and when it is only quasiconcave.

This paper extends the New Keynesian model by introducing wealth, in the form of government bonds, into the utility function. The extension modifies the Euler equation: in steady state the real interest rate is negatively related to consumption instead of being constant, equal to the time discount rate. Thus, when the marginal utility of wealth is large enough, the dynamical system representing the equilibrium is a source not only in normal times but also at the zero lower bound. This property eliminates the zero-lower-bound anomalies of the New Keynesian model, such as explosive output and inflation, and forward-guidance puzzle.

This paper extends the textbook New Keynesian model by introducing wealth, in the form of government bonds, in households' utility function. This extension modifies the properties of the New Keynesian IS curve: the real interest rate is now negatively related to output instead of being constant, equal to the time discount rate. As a result, when price rigidity and marginal utility of wealth are sufficient, the equilibrium admits a unique steady state, and this steady state is always a source, whether the economy is at the zero lower bound or away from it. These properties greatly simplify the analysis of the zero lower bound, and they eliminate several zero-lower-bound pathologies, such as the forward-guidance puzzle.

For each production or utility function, we can define the corresponding elasticities of substitution functions; but is the reverse true? This paper shows that yes, and that this link is fruitful. By inverting the system of partial differential equations defining the elasticities of substitution functions, we uncover an analytical formula which encompasses all production and utility functions that are admissible in Arrow-Debreu equilibria. We highlight the "Constant Elasticities of Substitution Matrix" (CESM) class of functions which, unlike the CES functions, does not assume uniform substitutability among all pairs of goods. A shortcoming of our method is that it permits only to control for local concavity while it is difficult to control for global concavity.