# Tagged Questions

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

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### Alternative to Subsets to generate k-combinations

I need to generare a huge number of k-combinations for a quite big set of numbers (more than 100), so I would avoid Subsets because it requires too much memory (it generates all subsets at once). I ...
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### How expand Binomial[n, k] for k >= 6? [closed]

Binomial[n, k] is converted to a polynomial only for k less than 6. ...
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### 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 O(2^N)*O(...
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### Find exponential generating function from the first few terms

The function FindGeneratingFunction computes the ordinary generating function of a sequence, given a sufficient number of initial terms. I have two questions in ...
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### Permutations on elements a>b && b>c

A={1, 2, 3, 4, 5} Permutations[A, {3}] I need to print all permutations where the first number is bigger than the second and the second number is bigger than the ...
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### Permutations and recurrence equation

First problem: I need to show all Permutations with length 4 of this elements {x, y, z, w, t} but with this condition: the element z mustn't be after element t. I ...
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### series combinations

is there any possibility of displaying all possible series of the form: "1+/-2^2+/-3^2+/-...+/-n^2", where one can choose the sign before the each term and knows the numbers of the terms in the series?...
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### Subsets or Outer?

How do I generate all possible subsets of a list of positive numbers (with at least 1 of them), given that each of these positive numbers subvariates itself on its input value and its multiplicative ...
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### Combinatorics: Placed errors

Consider a vector of length n where each element can take one of the values U, X, ...
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### How to compute the automorphisms of graphs with multiple edges?

I try to compute the Automorphisms of graphs with multiple edges from its AdjacencyMatrix but failed. The following code shows ...
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### How should my data be formatted for use with BetweennessCentrality?

A few weeks ago I asked this question. I am trying to upload my data which is an adjacency list for an undirected, unweighed graph and find the betweenness centrality. At the time I tried to use the ...
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### Generating all “from n choose k” configurations of a simple list [duplicate]

Suppose that I have a 1-D list called myList. Here's an example: myList = {"A", "B", "C", "D"}; I want to write (or find ...
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### How do I upload a graph as an adjacency list and find the betweenness centrality?

I have an undirected simple graph in a .txt file formatted as an adjacency list like this: 100 200 200 300 300 400 500 600 700 800 900 ... Every number is a node ...
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### Binomial[-1,-1]

According to various sources e.g. http://www.proofwiki.org/wiki/Definition:Binomial_Coefficient and Wolfram themselves http://functions.wolfram.com/GammaBetaErf/Binomial/02/ , the binomial ...
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### Challenge: Creating Compilable Permutations Function

As Mathematica's implemented Permutations function is not compilable I tried to write my very own Permutations implementation, called ...
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### Mathematica can't minimize a function

Mathematica seems not to be able to minimize this univariate function over integer arguments, $r>2, r \in \mathbb{Z}$. ...
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### Enumerate the 1-factors (perfect matchings) of $K_n$

Introduction I would like to enumerate the 1-factors, or (near-)perfect matchings, of the complete graph Kn. The adjacency list representation for Kn is basically { (x, y) | 1 ≤ x < y ≤ n }. For ...
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### Using IntegerPartitions for distinct integers

What I would like to do is to find a way to test how many ways m distinct integers from the set {1,..., n} where ...
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### Permutations with restrictions

I have a problem that can be modeled as: there are 8 boxes in total, and 60 different items. I want to put all items into boxes (all of them can be put into a single box). Now I want to find: 1) ...
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### 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 ...
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### Permutation count for sets with multiplicities

I am able to do a permutation counr for the set {a, a, b} which gives me 3 groups. I am happy with that result. However, if the set is ...