We consider a time-dependent economic market in order to show the existence of time-dependent market equilibrium n(which we call dynamic equilibrium). The model we are concerned with is the spatial price equilibrium model in the presence of excesses of supplies and of demands.

This kind of netwoek problem is directly incorporated into the Variational Inequality model, which provides not only the existence, but also the computation, the stability and the sensitivity of the equilibrium patterns.

The study of the time-dependent model seems to be important because it allows us to follow the evolution in time of prices and of commodities.