The distinct displacement-pattern conjecture for permutations

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Let SnS_n be the symmetric group, and let a displacement pattern be a tuple α=(a1,a2,…,an)\alpha=(a_1,a_2,\dots,a_n) recording the displacements of a permutation, with the entries distinct. The necessary conditions are

∑i=1mai≤m(n−m)(1≤m≤n),\sum^m_{i=1}a_i\leq m(n-m)\quad(1\leq m\leq n),

with equality for m=nm=n, together with the stated parity condition: if nn is even, the number of even entries is even, while if nn is odd, the number of odd entries is even. The distinct displacement-pattern conjecture. These necessary conditions are sufficient for the existence of a permutation π∈Sn\pi\in S_n with displacement pattern απ=α\alpha_\pi=\alpha. The conjecture is identified as a special case of the perfect Skolem set conjecture. The source gives no separate resolution status.

References

Primary source

Gustav Nordh, “Perfect Skolem sets”, arXiv:math/0506155 (2005).

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