Let $G$ be a 7-vertex planar graph.
Does exist such $G$ that complement of it = $\overline{G}$ that doesn't include 3-vetrex clique?
I've tried for $\overline{G}$ as graph where all vertexes have degree 2 and $\overline{G}$ doesn't include 3-vertex clique, but I can't proof that $G$ is plannar in this case.
It is equivalent to ask for $G$ to be a $7$-vertex planar graph with no $3$-vertex independent set: that is, with independence number $2$.
Searching the House of Graphs database with these criteria brings up 16 different examples. For example, this graph is the union of a $K_4$ and a $K_3$; it's planar, and its complement is the complete bipartite graph $K_{4,3}$, which does not contain a $3$-vertex clique because it has no odd cycles.
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