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2 votes
1 answer
211 views

The complexity of expansion ratio (Cheeger constant) of a graph

Let $G=(V(G), E(G))$ be a graph on $n$ vertices and let $S$ be a subset of $V(G)$. The boundary of $S$, denoted by $\partial S$, is the set of edges $(i, j)$ such that $i \in S$ and $j \in V(G) \...
Ranveer Singh's user avatar
3 votes
0 answers
107 views

Random graphs with prescibed degrees and triangles

In short: a random graph model generates (multi-)graphs with prescribed number of edges and minimal number of triangles for each vertex. Questions arise about the actual number of triangles and the ...
Matthieu Latapy's user avatar
2 votes
0 answers
69 views

Are two degree sequences compatible, for random simple graph generation?

Consider a set $V$ of $n$ vertices, and three degree sequences $a_i$, $b_i$ and $c_i$ such that $c_i = a_i+b_i$, $i=1..n$. Assume these degree sequences are graphical: there exist simple graphs (no ...
Matthieu Latapy's user avatar
5 votes
3 answers
411 views

Simple graphs with prescribed degrees as disjoint union of simple subgraphs with prescribed degrees

Consider a set $V$ of $n$ vertices, and three degree sequences $a_i$, $b_i$ and $c_i$ such that $c_i = a_i+b_i$, $i=1..n$. Assume these degree sequences are graphical: there exist simple graphs (no ...
Matthieu Latapy's user avatar
5 votes
2 answers
265 views

Triangle coloring in random graph

Given $m$ persons (men and women) and $n$ balls, each person randomly selects $3$ balls. Once all of them complete the selection process, we color the balls with $2$ colors, white and black, such that ...
lchen's user avatar
  • 367
186 votes
3 answers
96k views

Issue UPDATE: in graph theory, different definitions of edge crossing numbers - impact on applications?

QUICK FINAL UPDATE: Just wanted to thank you MO users for all your support. Special thanks for the fast answers, I've accepted first one, appreciated the clarity it gave me. I've updated my torus ...
user161819's user avatar
4 votes
2 answers
207 views

Fast uniform generation of random graphs with given degree sequences - any implementation?

The paper below presents a linear-time algorithm for uniform generation of random graphs with given degree sequences [1]. This is very interesting in practice, but I found no implementation. However, ...
Matthieu Latapy's user avatar
4 votes
0 answers
220 views

Navigation in a graph

The problem Let $G=(V,E)$ be a graph. $k = O\left(\log(|V|)\right)$ distinct vertices are picked randomly from $V$. We call the set of chosen $k$ vertices $T$. Assumptions about the graph: You may ...
real's user avatar
  • 323
8 votes
1 answer
630 views

Change in the average geodesic distance of a graph when flipping a single edge

Is there a way to determine how the average geodesic distance between nodes of a graph will change just by flipping (1) a single edge without having to traverse the whole graph like in the Djikstra ...
Rorsa's user avatar
  • 923