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24 votes
3 answers
4k views

What upper bounds are known for the diameter of the minimum spanning tree of $n$ uniformly random points in $[0,1]^2$?

Let $P$ be a pointset consisting of $n$ uniformly random elements of $[0,1]^2$. It is known that the diameter (greatest number of edges in any shortest path between two points) of the Delaunay ...
Louigi Addario-Berry's user avatar
12 votes
1 answer
400 views

Probability that random cubic polynomials meet in a square

Let $p_1(x)$ and $p_2(x)$ be cubic polynomials with random coefficients in $[-1,1]$. I wanted to compute the probability that $p_1$ and $p_2$ share at least one point within the square $[-1,1]^2$. Of ...
Joseph O'Rourke's user avatar
9 votes
1 answer
338 views

Visibility in a growing orchard

This is a variant on Polya's orchard problem.1,2 Suppose trees are planted randomly in the plane. The question is: How many trees are visible from the origin as their radii grow? More precisely, ...
Joseph O'Rourke's user avatar
6 votes
1 answer
273 views

Proof of a statement from Steele's "Probability theory and combinatorial optimization"

I am reading "Probability theory and combinatorial optimization" by J.M. Steele and am hung up on a statement made in Section 2.2 of Chapter 2, "Easy size bounds", in which it is stated (paraphrasing ...
Rosalie Dávila Perea's user avatar
5 votes
2 answers
323 views

Distribution over Penrose Tilings?

The set of possible kit-and-dart Penrose tilings is uncountably infinite. It would be very helpful to have some natural probability distribution $\mu$ over this set; such a distribution would allow ...
Bill Bradley's user avatar
  • 3,979
3 votes
1 answer
128 views

Random quads visible from a random point

Although the MO question Limit of lights in rooms was quickly closed, it suggests a related question: Q0. What is the probability that a random quadrilateral $Q$ is entirely illuminated from a ...
Joseph O'Rourke's user avatar
3 votes
0 answers
144 views

What is the probability that these four random areas can yield a tetrahedron?

This is inspired by this problem about randomly broken sticks that can form a triangle. It goes in a different direction than this generalization about randomly broken sticks that can form a ...
Wolfgang's user avatar
  • 13.4k
2 votes
1 answer
305 views

Distribution of area of randomly placed circles

I've searched the web now for ages to try and find a paper on the asymptotic distribution of the area of the union of randomly placed discs on the plane. Ideally, I would be looking for the discs to ...
Pavan Sangha's user avatar
2 votes
1 answer
121 views

Expected length of a certain kind of nearest-neighbor graph

Suppose I have sets of points $Z_1,\dots,Z_N$, such that $|Z_i|=m$ for all $i$, and where all $m\times N$ points are independently distributed uniformly at random in the unit square. Can someone give ...
Rosalie Dávila Perea's user avatar
0 votes
1 answer
176 views

Expected area of a pentagon formed from a randomly broken stick [closed]

Suppose we break a stick of length one at four randomly and independently chosen points and that the resulting pieces form a pentagon. Such a pentagon can be formed with probability $1-(5/16) = {11\...
John Smith's user avatar