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7 votes
0 answers
87 views

Universal point sets for 1-plane graphs

It is a notorious open problem to find a smallest set of $N$ points that permit any $n$-vertex planar graph to be drawn in the plane without crossings, using only those $N$ points as vertices, and ...
Joseph O'Rourke's user avatar
7 votes
0 answers
341 views

3-dimensional Cayley graph

I would like to see Cayley graphs drawn in 3-dimensional Euclidean space such that the vertices are represented by points and various shadows display the actions of the generators. For example, ...
David Richter's user avatar
5 votes
0 answers
198 views

"separators" for nonplanar graphs embedded in the plane

Given a nonplanar graph $G$ drawn in the plane with crossings. Does there exist a small ($o(|V(G)|$) subset $S$ of edges of $G$ such that after the removal of all edges that intersect or share an ...
Hao S's user avatar
  • 111
1 vote
0 answers
42 views

What lower bounds are known for pair crossing number and related questions in multigraphs?

So in terms of crossing number https://arxiv.org/pdf/1808.10480 gives a lower bound of $O(e^{2.5}/n^{1.5})$ for multigraphs with no face of length 2 with no node contained inside. What do we know ...
Hao S's user avatar
  • 111
1 vote
0 answers
97 views

Problem related to crossing number

Let $G$ be a graph embedded in the plane (with crossings). For $ F \subset E(G) $, denote by $c(F)$ the set of edges of $G$ that cross some edge in $F$. Denote $\delta(v)$ the set of edges with one ...
Hao S's user avatar
  • 111
1 vote
0 answers
77 views

Is there a variant of the crossing lemma for multigraphs with arbitrary embedding?

Suppose $G$ is a graph embedded in the plane with $m=|E(G)|$ edges and $n=|V(G)|$ vertices. Suppose $\operatorname{sim}(G)$, the simplification of $G$ contains $ m' \gg 3n $ edges. Call the set of ...
Hao S's user avatar
  • 111