Questions on the use of Mathematica in combinatorics, including the Combinatorica add-on package.

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6
votes
1answer
238 views

Young Tableaux Miscellanea

I have a problem which is mostly neatly described by using Young Tableaux. Mathematica seems to have these Tableaux built in, except that the Tableaux function is ...
4
votes
0answers
93 views

BipartiteMatching hangs with floating-point weights in Mathematica 7 (package Combinatorica)

I am trying to use Combinatorica's BipartiteMatching algorithm on a weighted graph. I need to use real numbers as weights. If I try the following ...
2
votes
0answers
193 views

Tools for finding minimal or almost-minimal graph vertex colorations in Mathematica v9?

I'm looking to compute minimum vertex colorations (s.t. no two vertices of the same color share an edge: http://en.wikipedia.org/wiki/Graph_coloring) for graphs in Mathematica v9 with potentially up ...
2
votes
0answers
389 views

Generating a function which outputs possible chemical reactions

I want to make a list of chemical reactions and I write them down in a $\require{mhchem}\LaTeX$ format. They are of the following form $$NA_n^i+MB_m^j \rightarrow \hat NA_{\hat n}^{\hat i}+\hat ...
1
vote
0answers
81 views

Is there a minor bug in Neal Alexander's TopologicalSortAll[]?

There is an amazing answer to this question: All possible topological orderings of a graph By Neal Alexander. However, as user "dark blue" (I am not this user) notes: ...
1
vote
0answers
134 views

How to sequentially select, from a large set of tuples (of matrices), those with a certain property

I'm interested in finding a computationally efficient way for selecting all tuples of matrices which have a certain property. The property I'm interested in is that I want the column sum, of f[the ...
1
vote
0answers
72 views

The number of real values assumed by combinations of complex roots of a decic

Define complex conjugate as the pair of complex numbers $a+bi,a-bi$. Assume you have 5 such pairs and they are the 10 roots $x_i$ of a 10th-deg equation with integer coefficients. In general, how many ...
1
vote
0answers
242 views

Get path to end nodes in directed (partially cyclic) graph

I have a large directed graph containing small loops. I would like to extract all paths to all end nodes (no VertexOutComponent) with a given path length $n$. I ...
0
votes
0answers
15 views

Efficiently find all connected subgraphs

Is there a way to generate all the connected subgraphs of a graph in mathematica without going through all the subsets of the nodes and checking if the subgraph is connected (which will be ...
0
votes
0answers
58 views

Identify columns of a huge matrix just polynomially many rows chosen at random

I am interested in the following problem in combinatorics $\Cap$ Probability. Let $\lambda \in \mathbb{N}$ be a parameter. Consider a matrix of $2^\lambda$ rows and $2^\lambda$ columns. Each column ...
-1
votes
0answers
52 views

Combinatorial exercise: Permutations in which a appears before c

i need to calculate something in Mathematica; We have the list A = {a,b,c,d,e} I need to find all permutations which will contain exactly 3 elements from A in which: a) element b appears only once ...