This paper examines the effect of entry barriers in a "mixture" oligopolistic market where a number of private firms maximize their profits and one government firm maximizes its share. The central government is assumed to control the number of private firms in that oligopolistic market. It will be shown that when the share of the government firm is sufficiently large, the number of firms at the free-entry equilibrium is smaller than that of welfare maximizing number of firms; we can obtain what may be called the "insufficient theorem" even under the condition that the outputs are homogenious and strategic substitutes.

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