Halin graph

Halin graph --- граф Халина.

[math]\displaystyle{ G }[/math] is a Halin graph if [math]\displaystyle{ G }[/math] is formed by embedding a tree having no degree-2 vertices in the plane, and connecting its leaves by a cycle that crosses none of its edges. Halin graphs are 3-connected and have a Hamiltonian circuit.