I apply Ricardo’s principle of comparative advantage to a theory of factor substitutability in a model with a continuum of worker and job types. Highly skilled workers have a comparative advantage in complex jobs. The model satisfies the distance‐dependent elasticity of substitution (DIDES) characteristic: substitutability between types declines with their skill distance. I analyze changes in relative wages due to human capital accumulation. The concept of a complexity dispersion parameter or compression elasticity is introduced. Empirical studies suggest its value to be equal to two: a 1 percent increase in the stock of human capital reduces the Mincerian return by 2 percent.

This paper discusses a general equilibrium model of the assignment of heterogeneous workers to heterogeneous jobs. Both jobs and workers are measured along a continuous one-dimensional scale. The composition of labor supply is represented by a distribution function. Highly skilled workers have an absolute advantage in all jobs and a comparative advantage in complex jobs. Equilibrium is characterized by a mapping of skills on complexities. The model is able simultaneously to explain the remuneration of skill, the allocation of skills to jobs, and variations in labor demand per job type. Estimation results for the Netherlands offer support for its relevance.

This paper describes a search model with a continuum of worker and job types, free entry and transferable utility. We apply a second-order Taylor expansion to characterize the equilibrium, derive the "cost of search" and show that it is decreasing in the substitutability of worker types. This cost of search is then decomposed into three components: unemployment, vacancy costs and mismatch. Our contact technology rules out congestion effects between different worker types and therefore exhibits increasing returns to scale. One third of those increasing returns in contacts are shown to be absorbed by firms and workers being more choosy. The resulting equilibrium is not efficient. Unemployment benefits can reduce the loss by serving as a search subsidy. Numerical simulations of the model show that our Taylor expansions are quite accurate.

This paper characterizes the equilibrium for a large class of search models with two-sided heterogeneity and on-the-job search. Besides the well-known congestion externalities, we show that on-the-job search in combination with monopsonistic wage setting without commitment creates a “business-stealing” externality. In the absence of congestion effects, this leads to excessive vacancy creation. Under wage setting with commitment this externality is absent because when posting a wage, firms take into account the expected productivity of future workers in their current jobs. If firms are able to make and respond to counteroffers, then they will not have to pay no-quit premia and this also leads to excessive vacancy creation.