Distribution of Income and Aggregation of Demand

We show that, under certain regularity conditions, if the distribution of income IS price independent and satisfies a condition on the shape of its graph, then total market demand, F(p), is monotone, i.e., given two positive prices p, and q, one has (p - q) . (F(p) - F(q)) < O. Similar assumptions on the distributions of endowments, yield a restricted monotonicity property on aggregate excess demand, where, now, wealth is determined by market prices. This is enough, however, to obtain uniqueness and stability of equilibrium for our Walrasian pure exchange model