Tagged Questions
0
votes
0answers
33 views
Generating partitions of a set with a specified size of the parts [duplicate]
I tried the following (inspired by the answer here)
myList = {a, b, c};
Needs["Combinatorica`"];
SetPartitions[myList]
and I got this answer,
...
4
votes
2answers
128 views
Partition a set into $k$ non-empty subsets
The Stirling number of the second kind is the number of ways to partition a set of $n$ objects into $k$ non-empty subsets. In Mathematica, this is implemented as ...
14
votes
6answers
847 views
Insert $+$, $-$, $\times$, $/$, $($, $)$ into $123456789$ to make it equal to $100$
Looks like a question for pupils, right?
In fact if the available math symbol is limited to $+$, $-$, $\times$, $/$ then it's easy to solve:
...
2
votes
0answers
194 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 ...
3
votes
0answers
160 views
Find all permutations with reversals / cyclic permutations removed
I have a list of all non-cyclic permutations of n labels. How can I get rid of all elements which are redundant in the sense that they are the inverse of another one. For instance if n=4, the ...
10
votes
3answers
267 views
Generating Linear Extensions of a Partial Order
Given a set $S$ and a partial order $\prec$ over $S$, I'm looking for a way to "efficiently" generate a list of linear extensions of $\prec$. Suppose the partial order is given by a ...
6
votes
2answers
414 views
Finding all partitions of a set
I'm looking for straightforward way to find all the partitions of a set.
IntegerPartitions seems to provide a useful start. But then things get a bit complicated.
...
13
votes
3answers
336 views
Determining all possible traversals of a tree
I have a list:
B={423, {{53, {39, 65, 423}}, {66, {67, 81, 423}}, {424, {25, 40, 423}}}};
This list can be visualized as a tree using ...
6
votes
1answer
201 views
Finding all length-n words on an alphabet that have a specified number of each letter
For example, I might want to generate all length n=6 words on the alphabet {A, B, C} that have one ...
11
votes
5answers
721 views
Partition a set into subsets of size $k$
Given a set $\{a_1,a_2,\dots,a_{lk}\}$ and a positive integer $l$, how can I find all the partitions which includes subsets of size $l$ in Mathematica? For instance, given ...
9
votes
4answers
442 views
Efficiently Visualising Very Large Data Sets (without running out of memory)
I have put a few really hard problems in combinatorics up against Mathematica 8. I'd have to say that it works really well, until you want to view the data. If you look at my question Advanced ...
16
votes
7answers
809 views
How to Derive Tuples Without Replacement
Given a couple of lists like a={1,2,3,4,6} and b={2,3,4,6,9} I can use the built-in Mathematica symbol ...
9
votes
3answers
248 views
Permutations[Range[12]] produces an error instead of a list
This input:
Permutations[Range[12]]
Results in this (error) output:
...
11
votes
7answers
1k views
Combination and Permutation
How could I obtain the list of all the groups of 5 numbers taken from Range[12] such that the 2 lists have an empty intersection :
...
