We address in this paper the question of the existence of a Social Welfare Function that would be sustainable and would allow us to obtain solutions to optimal growth models. We define sustainability by two new axioms called Never-decisiveness of the present and Never-decisiveness of the future....

We consider a model with an finite number of states of nature where short sells are allowed.

We consider a model with an inffnite number of states of nature, von Neumann - Morgenstern utilities, where agents have different probabil- ity beliefs and where short sells are allowed. We show that no-arbitrage conditions, deffned for ffnite dimensional asset markets models, are not sufficient...

Properness of preferences are useful for providing existences of an equilibrium and of supporting prices in Banach Lattices. In this paper we characterize completely properness and uniform properness for separable concave functions defined in L[subscript {plus}][superscript p]. We prove also...