The Schubert calculus conjecture on transversality of osculating Schubert intersections

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Let GrN+1(Polyd)Gr_{N+1}({\rm Poly}_d) be the Grassmannian of (N+1)(N+1)-dimensional subspaces of the space of complex polynomials of degree at most dd. Let F∙(ξ)\mathcal{F}_\bullet(\xi) be the osculating flag at ξ∈C∪∞\xi\in\mathbb{C}\cup\infty, and fix partitions w(1),…,w(n),w(n+1){\bf w}(1),\ldots,{\bf w}(n),{\bf w}(n+1) satisfying

∣w(1)∣+⋯+∣w(n+1)∣=(N+1)(N−d).|{\bf w}(1)|+\cdots+|{\bf w}(n+1)|=(N+1)(N-d).

For distinct complex numbers z1,…,znz_1,\ldots,z_n, write z=(z1,…,zn)z=(z_1,\ldots,z_n) and

I{w}(z):=Ωw(1)(F∙(z1))∩⋯∩Ωw(n)(F∙(zn))∩Ωw(n+1)(F∙(∞)).\mathcal{I}_{\{{\bf w}\}}(z):=\Omega_{{\bf w}(1)}\left(\mathcal{F}_\bullet(z_1)\right)\cap\cdots\cap\Omega_{{\bf w}(n)}\left(\mathcal{F}_\bullet(z_n)\right)\cap\Omega_{{\bf w}(n+1)}\left(\mathcal{F}_\bullet(\infty)\right).

The Schubert calculus conjecture. For generic z=(z1,…,zn)z=(z_1,\ldots,z_n), the intersection of Schubert varieties I{w}(z)\mathcal{I}_{\{{\bf w}\}}(z) is transversal. Here generic means that zz does not belong to a suitable proper algebraic subset of Cn\mathbb{C}^n. Transversality is known when at least n−1n-1 of the partitions are special, but the general case remains open.

References

Primary source

I. Scherbak, “Intersections of Schubert varieties and highest weight vectors in tensor products of sl_N+1-representations”, arXiv:math/0409329 (2005).

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