One is Almost Enough for Monopoly
证明，当产品耐用性和潜在进入同时存在时，竞争趋势可能被抵消：耐用品寡头无需承诺即可接近垄断利润，潜在进入反而可能让垄断者获得承诺能力，从而恢复垄断势力。
It has been argued that two factors-product durability and (potential) entry-may force a monopolist to price at marginal cost. This article shows that when these two forces coexist, the tendency toward competition may be negated. First, we prove that durable goods oligopolists without commitment powers may attain joint profits arbitrarily close to those of a monopolist with perfect commitment power. Second, we demonstrate that the presence of a potential entrant may enable a durable goods monopolist to act as if he had commitment power. Thus, potential as well as actual entry may restore monopoly power.