<P> The endowments where indeterminacy occurs systematically arise through time and therefore cannot be dismissed; the Arrow - Debreu - McKenzie model is thus fully subject to the dilemmas of factor price theory . </P> <P> Some have questioned the practical applicability of the general equilibrium approach based on the possibility of non-uniqueness of equilibria . </P> <P> In a typical general equilibrium model the prices that prevail "when the dust settles" are simply those that coordinate the demands of various consumers for various goods . But this raises the question of how these prices and allocations have been arrived at, and whether any (temporary) shock to the economy will cause it to converge back to the same outcome that prevailed before the shock . This is the question of stability of the equilibrium, and it can be readily seen that it is related to the question of uniqueness . If there are multiple equilibria, then some of them will be unstable . Then, if an equilibrium is unstable and there is a shock, the economy will wind up at a different set of allocations and prices once the convergence process terminates . However stability depends not only on the number of equilibria but also on the type of the process that guides price changes (for a specific type of price adjustment process see Walrasian auction). Consequently, some researchers have focused on plausible adjustment processes that guarantee system stability, i.e., that guarantee convergence of prices and allocations to some equilibrium . When more than one stable equilibrium exists, where one ends up will depend on where one begins . </P> <P> Research building on the Arrow--Debreu--McKenzie model has revealed some problems with the model . The Sonnenschein--Mantel--Debreu results show that, essentially, any restrictions on the shape of excess demand functions are stringent . Some think this implies that the Arrow--Debreu model lacks empirical content . At any rate, Arrow--Debreu--McKenzie equilibria cannot be expected to be unique, or stable . </P>

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