Felsner, Li and Trotter showed that the dimension of the adjacency poset of an outerplanar graph is at most 5, and gave an example of an outerplanar graph whose adjacency poset has dimension 4. We improve their upper bound to 4, which is then best possible.

中文翻译：

---

外平面图的邻接点

Felsner，Li和Trotter表明，一个外平面图的邻接点的维数最大为5，​​并给出了一个其邻接点的维度为4的外平面图的示例。我们将其上限提高到4，这样最好。