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Results tagged with co.combinatorics
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user 491
Enumerative combinatorics, graph theory, order theory, posets, matroids, designs and other discrete structures. It also includes algebraic, analytic and probabilistic combinatorics.
10
votes
4
answers
893
views
Count of binary matrices that avoids a certain sub-matrix
What is the number of $n$ by $m$ zero-one matrices that avoid a $2$ by $2$ sub-matrix of all ones?
For the motivation, I'm trying to generate nontrivial examples of differential posets, which are loc …
- 502
1
vote
Smith Normal Form and lower triangular Toeplitz Matrices
Some friends (including the original poster!) and I wrote up the proof of the result in this paper. The proof involves symmetric function theory.
- 502
8
votes
1
answer
3k
views
12 balls weighing puzzle
In an article describing the twelve balls weighing problem, the author mentions a solution that involves the finite projective plane of order 3, discovered by Rick Wilson. Does anyone know what this …
- 502
5
votes
The probabilistic method - reference to less challenging questions
We dealt with the probabilistic method in our undergrad randomized algorithms class at Berkeley, and used Mitzenmacher's book. Chapter 6 is about the probabilistic method and has a bunch of exercises …