The problem of deciding whether a biconnected planar digraph $G=(V,E)$ can be augmented to become an $st$-planar graph by adding a set of oriented edges $E' \subseteq V \times V$ is known to be NP-complete. We show that the problem is fixed-parameter tractable when parameterized by the size of the set $E'$.

翻译：判断双连通平面有向图 $G=(V,E)$ 能否通过添加定向边集 $E' \subseteq V \times V$ 扩展为 $st$-平面图的问题已知是NP完全的。本文证明，当以边集 $E'$ 的大小为参数时，该问题是固定参数可解的。