On the Differentiated Commodity Exchange and Pareto Improvement

In the condition that no other factors changed,Pareto Improvement and social welfare improvement can be achieve by exchanging differentiated commodity,whether market information is symmetric or asymmetric.However,some related limitations must be realized.For example,the exchange of differentiated commodity can lead to Pareto improvement but not Pareto Optimization;commodity differentiation may lead to the raise of production costs and transaction costs which may further diminish the welfare effects of differentiated commodity exchange in different degrees.