Economists traditionally tackle normative problems by computing optimal policy, i.e. the one that maximizes a social welfare function. In practice, however, a succession of marginal changes to a limited number of policy instruments are implemented, until no further improvement is feasible. I...

This paper presents a simple, analytically solvable Chamberlinian agglomeration model. As in the canonical core-periphery (CP) model, two agglomerative forces are at work. However, the present model exhibits a "pitchfork bifurcation" rather than the "tomahawk bifurcation" of the CP model.

We survey the literature on social networks by putting together the economics, sociological and physics/applied mathematics approaches, showing their similarities and differences. We expose, in particular, the two main ways of modeling network formation. While the physics/applied mathematics...

How do individuals shape societies? How do societies shape individuals? This paper develops a framework for studying the connections between micro and macro phenomena. The framework builds on two ingredients widely used in social science - population and variable. Starting with the simplest case...

We study a search model where workers can send multiple applications to high and low productivity firms. Firms that compete for the same candidate can increase their wage offers as often as they like. We show that there is a unique equilibrium where workers mix between sending both applications...

Wealthy individuals often voluntarily provide public goods that the poor also consume. Such philanthropy is perceived as legitimizing one's wealth. Governments routinely exempt the rich from taxation on grounds of their charitable expenditure. We examine the normative logic of this exemption. We...

When similar patterns of expansion and contraction are observed across sectors, we call this a business cycle. Yet explaining the similarity and synchronization of these cycles across industries remains a puzzle. Whereas output growth across industries is highly correlated, identifiable shocks,...

We consider the welfare effects of the emigration of workers who produce a public good (knowledge). We distinguish between the knowledge diversion and knowledge creation effects of such emigration, and show that the remaining residents of a country can gain from emigration, even when tastes for...

This paper proposes a matching model that distinguishes between job creation by existing firms and job creation by firm entrants. The paper argues that vacancy posting and job destruction on the extensive margin, i.e. from firms that enter and exit the labour market, represents a viable...

Violence and housing insecurity are horrible events that may be intertwined, with violence possibly forcing victims to abandon their accommodations and housing insecurity depriving people of the safety of a home or placing them in compromised circumstances. This study uses national, prospective,...