"In this paper, we construct a simple model based on heterogeneity in workers' productivity and homogeneity in their working schedules. This simple model can generate unemployment, even if wages adjust instantaneously, firms are perfectly competitive, and firms can perfectly observe workers'...

"We analyze optimal monetary policy in an endogenous sticky price model. Similar models with exogenous sticky prices can deliver multiplicity of equilibria. Multiplicity of equilibria is a necessary condition for expectation traps to explain the variation across time and countries of inflation...