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Research notes on every problem, and a library of the papers behind them. Built from the open erdos repository.

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Source. Conjecture 4, PDF p. 2 of arXiv:math/0604347v2.

Statement

Interpret the statement for an integer k≥2k\geq2. Suppose A1,…,AkA_1,\ldots,A_k are pairwise disjoint left cosets of subgroups H1,…,HkH_1,\ldots,H_k in a group GG. Then there are indices i<ji<j such that

gcd⁡([G:Hi],[G:Hj])≥k.\gcd([G:H_i],[G:H_j])\geq k.

The printed statement does not separately say k≥2k\geq2, but its conclusion requires a pair i<ji<j, so that range is implicit and is made explicit here. It also does not separately say that the subgroup indices are finite, although its displayed greatest common divisor uses them as ordinary integers. This page preserves that second implicit convention rather than silently adding a finite-index hypothesis.

Proof scope. This is a conjecture attributed to Sun, not a proved theorem in this source.