« first day (3085 days earlier)      last day (815 days later) » 

Martin Sleziak
Martin Sleziak
12:28 AM
1
Q: Completing a tree to a 2-connected outerplanar graph

Felix GoldbergLet $T$ be a given (finite) tree. Question 1: Is it always possible to add edges to $T$ to obtain a $2$-connected outerplanar supergraph $G$? Question 2: If the answer to Question #1 is negative, can the trees for which it is possible be characterized? Question 3( Defect form of Question 1): Let ...

graph-theory trees embeddings planar-graphs outerplanar-graphs
Outerplanar graph
In graph theory, an outerplanar graph is a graph that has a planar drawing for which all vertices belong to the outer face of the drawing. Outerplanar graphs may be characterized (analogously to Wagner's theorem for planar graphs) by the two forbidden minors K4 and K2,3, or by their Colin de Verdière graph invariants. They have Hamiltonian cycles if and only if they are biconnected, in which case the outer face forms the unique Hamiltonian cycle. Every outerplanar graph is 3-colorable, and has degeneracy and treewidth at most 2. The outerplanar graphs are a subset of the planar graphs, the subgraphs...
 
 
11 hours later…
Martin Sleziak
Martin Sleziak
11:00 AM
Down to 98 manual ones in questions and answers, now! — David Roberts 2 days ago
@DavidRoberts Thank you a lot for your ongoing effort! — Emil Jeřábek 21 hours ago
I am just curious, when somebody comes and says: "Why did you edit those links? They should have stayed as they were."
SEDE now returns 383 posts with front.math.ucdavis.edu.
The search for url:"*front.math.ucdavis.edu*" now returns 378 posts.
On November 2 there were about 480 posts: chat.stackexchange.com/transcript/10243/2021/11/2 On January 2 about 430: chat.stackexchange.com/transcript/10243/2022/1/2
The posts where such links was edited away: data.stackexchange.com/mathoverflow/query/1070272/…
Users who often removed such links: data.stackexchange.com/mathoverflow/query/1468213/…
However, number of the links which have to be edited manually are probably more important.
At the time of my post on meta:
> All links starting with front.math.ucdavis.edu/math/ followed by 00 to 06 were before 2007. SEDE returns 194 posts and 63 comments.
Now this query returns 96 posts. (And 108 posts where such link has been edited away.)
 

« first day (3085 days earlier)      last day (815 days later) »