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57 votes
4 answers
15k views

Connectivity of the Erdős–Rényi random graph

It is well-known that if $\omega=\omega(n)$ is any function such that $\omega \to \infty$ as $n \to \infty$, and if $p \ge (\log{n}+\omega) / n$ then the Erdős–Rényi random graph $G(n,p)$ is ...
Matthew Kahle's user avatar
12 votes
3 answers
3k views

Area Enclosed by the Convex Hull of a Set of Random Points

Consider $n$ points generated randomly and uniformly on a unit square. What is the expected value of the area (as a function of $n$) enclosed by the convex hull of the set of points?
user18011's user avatar
  • 123
21 votes
2 answers
548 views

Do these polynomials have alternating coefficients?

In answering another MathOverflow question, I stumbled across the sequence of polynomials $Q_n(p)$ defined by the recurrence $$Q_n(p) = 1-\sum_{k=2}^{n-1} \binom{n-2}{k-2}(1-p)^{k(n-k)}Q_k(p).$$ Thus: ...
François G. Dorais's user avatar
10 votes
2 answers
2k views

Probability of Generating a Connected Graph

$N$ points are generated randomly within a unit square, with a uniform distribution. What is the probability that the points form a connected graph, given that two points are connected if the distance ...
Melvin Gauci's user avatar
7 votes
2 answers
1k views

Edge probability for connected Erdős–Rényi model

Consider the Erdős–Rényi model $G_{n,p}$ with corresponding probability measure $\mathbb{P}_{n,p}$. For any two vertices $x,y$, $\mathbb{P}_{n,p}[E_{x,y}]=p$, where $E_{x,y}$ is the event that there ...
jondal's user avatar
  • 71
4 votes
1 answer
245 views

Probability of a vertex being a "degree-celebrity" in a random graph

If $G(n,p)$ is a random graph of the Erdös-Rényi model, what is the probability that $\mathrm{deg}(v)\gt\mathrm{deg}(u)\ \forall u\in\mathrm{adj}(v)$ Please feel free to relate answers to other ...
Manfred Weis's user avatar
  • 13.2k
4 votes
0 answers
617 views

Expected number of components with multiple cycles in a subgraph of a square lattice

Short version Is there an understanding of the emergence and subsequent disappearance of components with zero, one, or more cycles in a random subgraph of a square or cubic lattice, as the edge-...
Niel de Beaudrap's user avatar
4 votes
2 answers
4k views

Expected global clustering coefficient for Erdős–Rényi graph

What is the expected global clustering coefficient $\mathbb{E}[C_{GC}]$ for the Erdős–Rényi random graph (ER-graph) $\mathcal{G}(n,p)$ (expectation is over the ensemble of all ER-graphs) as $n \...
Fabian Ying's user avatar
3 votes
1 answer
192 views

Discrepancy of random bipartite graphs

This is a crosspost from MathStackExchange (original question). Fix $k>0$ and let $X, Y$ be two vertex sets of size $n$ a positive integer (we're interested in the limit $n\to \infty$). Define a ...
Antoine Labelle's user avatar
3 votes
1 answer
206 views

Component properties in Euclidean graphs with distance threshold

In the context of Euclidean graphs with vertices randomly embedded in either a 2D plane (for instance square with length $L$) or in 3D (similarly, cube of side $L$), where an edge between two given ...
user929304's user avatar
2 votes
1 answer
426 views

Random subgraph properties

Consider a graph $G$ of $N$ vertices and $M$ edges, and assume $G$ has typical complex network properties: it is not necessarily connected, but it has a high clustering coefficient and a giant ...
lenhhoxung's user avatar
1 vote
0 answers
78 views

Canonical representation of the a probability distribution for Hammersley Clifford Theorem

I'm reading the following paper http://www2.stat.duke.edu/~scs/Courses/Stat376/Papers/GibbsFieldEst/BesagJRSSB1974.pdf On page 7 they give the result that $$Q(\textbf{x}) = \sum_{1 \leq i \leq n} ...
Pavan Sangha's user avatar
1 vote
1 answer
152 views

Discrepancy of random bipartite graphs (2)

This question is a modification of the one asked here, which turned out to ask for something too strong to be true. Given $k>0$ and a positive integer $n$, let $X, Y$ be two vertex sets of size $n$ ...
Antoine Labelle's user avatar