Function Repository Resource:

DerangementQ (1.0.0) current version: 1.1.0 »

Test whether the permutation list is completely scrambled

Contributed by: Wolfram Staff

ResourceFunction["DerangementQ"][p]

tests whether the permutation list p is such that no element appears in its original position.

Examples

No elements are in their original places:

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For even n, the list {n,…,3,2,1} is a derangement:

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The chances are about 1 in 3 that a permutation is a derangement:

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