# Questions tagged [permutations]

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### “Partial” invert a one-way permutation

First of all, to my best understanding, traditionally, if $f$ is a one-way function that maps a length $l$ bit string to another length $l$ bit string (i.e., $f:\{0,1\}^l\rightarrow\{0,1\}^l$), then ...
111 views

### Effect of constraints Density on the hardness of Betweness problem

Betweeness problem is well known NP-complete permutation problem. Given a family $M$ of triples $(a_i, a_j, a_k)$, the problem is to decide whether a permutation $\Phi$ of elements $a_1, a_2, ..., a_n$...
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### Algorithm for calculating substitution combination with ordering

I need to calculate the combinations of elements with a substitution element. For example for elements [A,B] if the substitution is X the results should be ...
503 views

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### List the $k$-faces of an $n$-dimensional simplex

Suppose you are given an $n$-dimensional simplex S = [ 0 1 ... n ] which for the time being we think of as an ascending array of numbers from $0$ to $n$. Given \$...
208 views

### Lowerbounds for in-situ permutation

What is the best known lowerbound for the worst case complexity of in-situ permutation (also called in-place rearrangement)? Has there been any reported progress after the 1970's article by Knuth (...
762 views

### Set Cover for Permutation Matrices

Given a set S of nxn permutation matrices (which is only a small fraction of the n! possible permutation matrices), how can we find minimal-size subsets T of S such that adding the matrices of T has ...
637 views

### How to compute ROOK Polynomials for NxM Matrices [closed]

How to compute ROOK Polynomials for NxM Matrices for k objects ?