Oligopoly price discrimination and resale price maintenance

Oligopoly price discrimination in the retail market prevents a manufacturer from inducing optimal retail margins through any wholesale price, This motivates the manufacturer to impose resale price maintenance, In a model of third-degree price discrimination by rival retailers, a retail price ceiling (or floor) enables the manufacturer to restore the first best. Imposing a fired retail price is generally not optimal because the manufacturer wants to eliminate price discrimination based on consumers' abilities to switch retailers, not based on consumers' valuations. Under resale price maintenance, welfare may either increase or decrease, and it may increase even when total output is reduced.