Conjecture on the cut locus of lifted Fermat hypersurfaces

Let π:S2n+1CPn\pi:\mathbb{S}^{2n+1}\to\mathbb{CP}^n be the quotient map, let

X(d)={[z0:z1::zn]CPn:i=0nzid=0},X(d)=\left\{[z_0:z_1:\cdots:z_n]\in\mathbb{CP}^n:\sum_{i=0}^n z_i^d=0\right\},

and set X~(d)=π1(X(d))\tilde{X}(d)=\pi^{-1}(X(d)). Here Zd(n+1)\mathbb{Z}_d^{\star(n+1)} denotes the (n+1)(n+1)-fold topological join of Zd\mathbb{Z}_d, and ×Zd\times_{\mathbb{Z}_d} denotes the diagonal action of Zd\mathbb{Z}_d. Cut-locus conjecture. The cut locus of X~(d)S2n+1\tilde{X}(d)\subseteq\mathbb{S}^{2n+1} is

Zd(n+1)×ZdS1.\mathbb{Z}_d^{\star(n+1)}\times_{\mathbb{Z}_d}\mathbb{S}^1.

This conjecture gives a geometric description of the cut locus of the lift of a Fermat-type complex hypersurface under the Hopf quotient. The supplied text does not state any partial results or resolution, so its status remains open.

Sources & referencesView supporting material

Primary source

Sachchidanand Prasad, “Cut Locus of Submanifolds: A Geometric and Topological Viewpoint”, arXiv:2303.14931 (2023).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.