Please Help me solve this interesting combinatorics Problem.

Revision en2, by Another_Alt_123, 2023-02-18 07:34:30

Let U = {1, 2,...,n}, where n is a large positive integer greater than 1000. Let k be a positive integer less than n. Let A, B be subsets of U with |A| = |B| = k and A ∩ B = ∅. We say that a permutation of U separates A from B if one of the following is true.

  • All members of A appear in the permutation before any of the members of B.

  • All members of B appear in the permutation before any of the members of A.

How many permutations of U separate A from B?

Tags permutations, combinations

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en2 English Another_Alt_123 2023-02-18 07:34:30 6
en1 English Another_Alt_123 2023-02-18 07:33:32 527 Initial revision (published)