Fixed-point conjecture for Grassmannian braid-group actions

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Let d=gcd⁡(k,n)>1d=\gcd(k,n)>1, assume n=k+ℓ+1n=k+\ell+1, and assume C[Gr⁡(k,n)]\mathbb{C}[\operatorname{Gr}(k,n)] is of infinite type. Let Br⁡d\operatorname{Br}_d be the braid group with generators σi\sigma_i for i∈[d−1]i\in[d-1]. A fixed point, stable fixed point, unstable fixed point, cluster monomial, and prime non-real element are understood as defined in the source.

Braid-group fixed-point conjecture. For every i∈[d−1]i\in[d-1], if (k,n)(k,n) is (3,9)(3,9) or (4,8)(4,8), every unstable fixed point of σi\sigma_i in C[Gr⁡(k,n)]\mathbb{C}[\operatorname{Gr}(k,n)] is a cluster monomial; and for every (k,n)(k,n) under the stated hypotheses, every stable fixed point of σi\sigma_i is prime non-real.

This combines two claims about the stable and unstable fixed points of braid-group generators. The supplied text gives no resolution status.

References

Primary source

James Drummond, Ömer Gürdoğan and Jian-Rong Li, “Tropical symmetries of cluster algebras”, arXiv:2601.19779 (2026).

Additional references

3 papers in this index state this conjecture (2012–2026). The statement above is taken from the most recent of them; the others are arXiv:1907.10023, arXiv:1210.3219.

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