We analyse a Ramsey economy when net investment is constrained to be non negative. We prove existence of a competitive equilibrium when utility need not hold. The analysis is carried out by means of direct and technically standard strategy.

We introduce consumption externalities into a general equilibrium model with arbitrary consumption sets. To treat the problem of existence of equilibrium, a condition of no unbounded arbitrage, extending the condition of Page (1987) and Page and Wooders (1993, 1996) is defined. It is proven that...