Properties of minimal charts and their applications II
Teruo Nagase, Akiko Shima · Hiroshima Mathematical Journal · 2009
Let $\Gamma$ be a minimal chart with exactly seven white vertices. In this paper, we show that $\Gamma$ is a chart of type $(7),(5,2),(4,3),(3,2,2)$ or $(2,3,2)$ if necessary we change the labels. We investigate minimal charts with loops or lenses.