In our attempt to define GPC, Tudor Onea & I reject the idea that GPC does not exist in unipolarity... doi.org/10.1093/acrefo…
...because a single great power can become preeminent while other GPs continue to exist and maintain their rank. A. F. K. Organski's stylized "power pyramid" diagram reflects this notion that a dominant power can head up an order that includes several GPs.