Wolfram Function Repository
Instant-use add-on functions for the Wolfram Language
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Compute the major index of a permutation
ResourceFunction["PermutationMajorIndex"][p] gives the major index of the permutation p. |
Since descents of this permutation are at positions 2 and 4, the major index is 2+4=6:
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There are six permutations of length 4 with major index 3:
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There is an equal number of permutations of length 4 with three inversions:
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The number of permutations of length n with major index k and inversion count i is the same as the number of permutations of length n with major index i and inversion count k:
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The number of permutations of length 4 with given major index and inversion count:
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