A colleague saw the same model-calibrating the elasticity of demand facing a Cournot oligopolist as a function of the number of firms in the industry--described at the University of Chicago and at M. I. T. A Chicago economist derived the formula and said, "Look at how few firms you need to get close to infinite elasticities and perfect competition. " An M. I. T. economist derived the same formula and said, "Look at how large n has to be before you get anywhere close to an infinite elasticity and perfect competition. "