We extend the analysis of monopoly third-degree price discrimination to the empirically important case where marginal costs also differ between markets. Differential pricing then reallocates output to the lower-cost markets, hence welfare can increase even if total output does not, unlike under...

This paper analyzes welfare under differential versus uniform pricing across oligopoly markets that differ in costs of service. We establish necessary and sufficient conditions on demand properties---cross/own elasticities and curvature---for differential pricing by symmetric firms to raise...