A note on "An Inframarginal Analysis of the Ricardian Model"

This is a note about Cheng et al's paper, in which we consider a dual structure of division of labor and trade in the model of Cheng et al that is missed by the authors. While the inclusion of the dual structure will not change major results in the paper of Cheng, et al., it explores an interesting way to use a general equilibrium model to describe a dual structure with underemployment in a transitional period of economic development.