Strongly light subgraphs in the 1-planar graphs with minimum degree 7

A graph is {\em $1$-planar} if it can be drawn in the plane such that every edge crosses at most one other edge. A connected graph $H$ is {\em strongly light} in a family of graphs $\mathfrak{G}$, if there exists a constant $\lambda$, such that every graph $G$ in $\mathfrak{G}$ contains a subgraph $K$ isomorphic to $H$ with $\deg_{G}(v) \leq \lambda$ for all $v \in V(K)$. In this paper, we present some strongly light subgraphs in the family of $1$-planar graphs with minimum degree~$7$.Comment: 6 pages, 6 figures, http://amc-journal.eu/index.php/amc/article/view/564. in Ars Mathematica Contemporanea, 201

A note on 1-planar graphs with minimum degree 7

It is well-known that 1-planar graphs have minimum degree at most 7, and not hard to see that some 1-planar graphs have minimum degree exactly 7. In this note we show that any such 1-planar graph has at least 24 vertices, and this is tight.Comment: 4 page