Ross–Yong's K-theoretic Kohnert rule for Grothendieck polynomials

For a permutation wSnw\in S_n, let Gw\mathfrak{G}_w be the Grothendieck polynomial, let KKoh(w){\sf KKoh}(w) be the family of KK-Kohnert diagrams generated from the diagram of ww, and let wt(E)\mathrm{wt}(E) be the weight of a diagram EE. For αZ0n\alpha\in\mathbb{Z}_{\geq 0}^n, write KKoh(w,α){\sf KKoh}(w,\alpha) for the diagrams of weight α\alpha and PD(w,α)\mathrm{PD}(w,\alpha) for pipe dreams of weight α\alpha.

Ross–Yong's Grothendieck-polynomial conjecture. For every permutation wSnw\in S_n,

Gw=EKKoh(w)(1)wt(E)(w)xwt(E).\mathfrak{G}_w=\sum_{E\in{\sf KKoh}(w)}(-1)^{|\mathrm{wt}(E)|-\ell(w)}x^{\mathrm{wt}(E)}.

Equivalently,

#KKoh(w,α)=#PD(w,α)for every αZ0n.\#{\sf KKoh}(w,\alpha)=\#\mathrm{PD}(w,\alpha)\quad\text{for every }\alpha\in\mathbb{Z}_{\geq 0}^n.

Robichaux disproved this rule, including an explicit counterexample in S8S_8; hence the conjecture is refuted.

Sources & referencesView supporting material

Primary source

Avery St. Dizier, “Counterexamples to Robichaux's conjecture for Grothendieck polynomials”, arXiv:2606.02257 (2026).

Additional references

2 papers in this index state this conjecture (2022–2026). The statement above is taken from the most recent of them; the others are arXiv:2206.08993.

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