Subscribe to the weekly news from TrueShelf

## Trees and non-planarity

Let $V$ be a set of vertices, and let $T_1=(V,E_1)$, $T_2=(V,E_2)$, and $T_3=(V,E_3)$ be three trees on the vertices of $V$ with disjoint sets of edges: $E_1\cap E_2 = E_2\cap E_3 = E_3\cap E_1 = \emptyset$. Let $G=(V,E_1\cup E_2 \cup E_3)$ be the union of the three trees.

Prove that $G$ is not planar.

0

0

0
0

0

0

0

0

0

0