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 answers only not deleted user 11142

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.

2 votes

A plane graph problem

This is Cauchy's Combinatorial Lemma, which is Lemma 26.8 in Pak's book.
Igor Rivin's user avatar
  • 96.4k
1 vote

Lower bound on diameter of trivalent graphs

To amplify on Fedor's answer, random graphs come close to this bound, for a lot more color see the ancient (but still useful) 1987 paper by Fan Chung.
Igor Rivin's user avatar
  • 96.4k
1 vote
Accepted

Generalizing Steinitz's theorem

Well, no direct generalization is known. One related result (which seems to have come out of an attempt to generalize Steinitz) is this paper by D. Eppstein and E. Mumford. However, since Steinitz' th …
Igor Rivin's user avatar
  • 96.4k
3 votes

Is the following graph well known?

It is the "generalized Kneser graph". See the Wikipedia article on "Kneser graph" and references therein. See also a paper by B. Mohar and I. Rivin on related geometric questions...
Igor Rivin's user avatar
  • 96.4k
0 votes

Bounds on spanning tree for sparse graphs

Yes. See this paper: www.intlpress.com/JOC/p/2010/JOC-1-2-a1-Thomassen.pdf (Carsten Thomassen, spanning trees and orientations in graphs; google shows you the full text...), and references therein ( …
Igor Rivin's user avatar
  • 96.4k
1 vote

Spanning trees of $H \cup e$ in terms of $H$

This seems to be exactly the subject of: http://gradworks.umi.com/31/89/3189623.html In particular, the "Feussman formula" cited in the abstract would seem to be useful (this is used to prove the ma …
Igor Rivin's user avatar
  • 96.4k
3 votes

Proving that every graph is an induced subgraph of an r-regular graph

In that case, the answer is given by Classification of degree (bi-)sequences of bipartite graphs? You call the vertices of your graph red, and you want to have a collection of blue vertices, so that t …
Igor Rivin's user avatar
  • 96.4k
7 votes
Accepted

Isomorphic regular graphs

The asymptotic number of $m$-regular graphs on $N$ vertices is well understood and can be found, for example, in Bollobas' Random Graphs (the argument uses Bollobas' "configuration model"). With proba …
Igor Rivin's user avatar
  • 96.4k
1 vote

Construct a Random graph from the degree distribution,

See http://www.stat.berkeley.edu/~sourav/beam-yale-trans.pdf
Igor Rivin's user avatar
  • 96.4k
3 votes

positive weighted directed graphs

The set of weightings whose sum vanishes along each cycle corresponds exactly to gradients of functions on vertices (in other words, the weight of an edge is $f(h) - f(t),$ where $h, t$ are head and t …
Igor Rivin's user avatar
  • 96.4k
3 votes

Faithfully embeddable graphs

To see whether a complete graph (also known as a finite metric space) is isometrically embeddable in $\mathbb{E}^n,$ one needs to check the signs of various minors of the Cayley-Menger matrix, describ …
Igor Rivin's user avatar
  • 96.4k
5 votes
Accepted

Number of spanning subgraphs of the complete bipartite graph $K(m,n)$

This is only known explicitly for $m=4$. A decent survey is here: http://www.math.ru.nl/~bosma/Students/JannekevandenBoomen/JannekevdBoomenMScthesis.pdf
Igor Rivin's user avatar
  • 96.4k
3 votes

How many triangles can a connected graph with $n$ vertices and $m$ edges have?

This question (together with massive generalizations) is answered in I. Rivin's 2001 paper.
Igor Rivin's user avatar
  • 96.4k
6 votes

Distance-regular graphs

See http://www.win.tue.nl/~aeb/ (the web page of A. Brouwer) -- he has data, and I am guessing that he would be receptive to questions, as well.
Igor Rivin's user avatar
  • 96.4k
5 votes
Accepted

An upper bound for number of triangles in a graph

The property is that the graph be sparse, since it is easy to show that the number of triangles is $O(|E|^{3/2}),$ so as long as $E = O(V),$ your result holds. For the (simple) proof and sharp extensi …
Igor Rivin's user avatar
  • 96.4k

1
2 3 4 5
8
15 30 50 per page