김연식 Y . S . Kim
DOI: JANT Vol.10(No.2) 4-8, 1972
We consider the class ∏_k of all k-degenerate graphs, for k a non-negative integer. The class ∏_0 and ∏₁ are exactly the classes of totally disconnected graphs and of forests, respectively; the classes ∏₂ and ∏_5 properly contain all outerplanar and planar graphs respectively. The advantage of this view point is that many of the known results for chromatic number and point arboricity have natural extensions, for all larger values of k. The purpose of this note is to show that a graph G is (P³)-realizable if G is planar and 3degenerate.