Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options not deleted user 6322

Questions about the branch of combinatorics called graph theory (not to be used for questions concerning the graph of a function). This tag can be further specialized via using it in combination with more specialized tags such as extremal-graph-theory, spectral-graph-theory, algebraic-graph-theory, topological-graph-theory, random-graphs, graph-colorings and several others.

1 vote

Deciding whether a given graph has an f-factor or not!

Yes; in fact, one can find in polynomial time a subgraph that is "as close as possible" to being an $f$-factor, if no $f$-factor exists. See, for example, Hell-Kirkpatrick: http://www.sciencedirect.co …
Gregory J. Puleo's user avatar
8 votes
Accepted

How many uniquely colored degree two vertices in 3-coloring of subcubic graph?

No such graph exists (that is, you cannot have a subcubic graph with three degree-$2$ vertices all forced to the same color). Suppose that such a graph exists; we may assume the graph is connected. Th …
Gregory J. Puleo's user avatar
9 votes
Accepted

What is the correct statement of this Erdös-Gallai-Tuza problem generalizing Turan's triangl...

I hope I am not violating any kind of MathOverflow etiquette by responding to a question 2 years after it has been asked, but your question is answered in the following preprint of mine that just hit …
Gregory J. Puleo's user avatar
6 votes

Proving Hall's marriage theorem using Sperner's lemma

In addition to Carlo Beenakker's answer that gives Hall via Sperner directly, I think you can also get it by applying Hall's Theorem for Hypergraphs as follows. Let $G$ be a bipartite graph with parti …
Gregory J. Puleo's user avatar
5 votes
Accepted

List chromatic index of a particular graph

Greedy coloring works here to show $2p$-choosability, I believe, and the hypothesis that $p$ is prime doesn't appear to be necessary. Write the cliques as $A = \{a_1, \ldots, a_{p+1}\}$ and $B = \{b_1 …
Gregory J. Puleo's user avatar
12 votes
Accepted

Blinking graphs

This question seems quite similar to the problem of parity domination. Let $S$ be the set of vertices with label $1$. The condition that $S$ flips to its complement after updating is equivalent to the …
Gregory J. Puleo's user avatar