Source: wikibot/halin-graph
= Halin graph
{wiki=Halin_graph}
A Halin graph is a type of graph that is formed from a connected, planar graph, specifically by taking the dual of a polyhedron and then removing its outer face. It can also be constructed by taking a tree (specifically, a connected graph without cycles), doubling its edges, and connecting the resulting vertices to form a polyhedral structure. Halin graphs are named after Rudolf Halin, who contributed significantly to their study.