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10 votes
2 answers
441 views

Graph planarization via rewiring

Let $G$ be a nonplanar graph (undirected) of $n$ nodes and $e$ edges, with $e \le 3n-6$. Define a rewiring move as replacing edge $(a,b)$ with edge $(a,c)$. The result must be a simple graph (no loops,...
Joseph O'Rourke's user avatar
3 votes
0 answers
222 views

Reconstructing plane graphs from degree- and face-sequences

Let $G$ be a plane $3$-connected graph; so it partitions the plane into regions bounded by faces. Let $\mathrm{deg}_v$ be the sequence of vertex degrees of $G$, and $\mathrm{deg}_f$ be the sequence of ...
Joseph O'Rourke's user avatar
2 votes
1 answer
95 views

Dipping into sets of parallel edges in graph drawings

Given a multigraph embedded in the plane call a maximal set of parallel edges between $u,v$ such that only one of the induced faces contains nodes besides $u$ or $v$ a topologically parallel set (tell ...
Hao S's user avatar
  • 111
1 vote
1 answer
114 views

Removing a face from 4-connected planar graph

After removing a face (vertices along with edges) of a 4-connected planar graph, is the remaining graph 4-connected? Alternatively under what conditions is this true?
Agile_Eagle's user avatar
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
1 vote
0 answers
149 views

Determine sub-polygon from line segments with known member connectivity

Test Polygon: Consider the following polygon as attached. Let the known parameter be as follows: •Member to member connectivity, i.e. it is known that A – B, X – E, F – B, etc. for all the members. •...
sidb's user avatar
  • 19