We investigate the possibility for two vertically related firms to at least partially collude on the wholesale price over an infinite horizon to mitigate or eliminate the effects of double marginalisation, thereby avoiding contracts which might not be enforceable. We characterise alternative...

We show that supply functions cannot be classified as either strategic complements or substitutes according to the twofold criterion advanced by Bulow et al. (1985). This is because while the slope of the best reply is univocally positive, this is not the case with the sign of the cross...