Orthogonal tangent intersections characterize quadrics

Let MRnM\subset\mathbb R^n, n3n\geq 3, be an open patch of a hypersurface of class C2C^2, and let Γ1,Γ2\Gamma_1,\Gamma_2 be space curves. Orthogonal-intersection conjecture. If for every pMp\in M there are unique intersection points u1=Γ1TpMu_1=\Gamma_1\cap T_pM and u2=Γ2TpMu_2=\Gamma_2\cap T_pM of the tangent hyperplane TpMT_pM with Γ1\Gamma_1 and Γ2\Gamma_2, respectively, and the vectors u1p,u2pTpMu_1-p,u_2-p\in T_pM are orthogonal with respect to the second fundamental form IIp\mathrm{II}_p of MM at pp, then MM is contained in a quadric. The statement is proposed as a far-reaching local generalization of the paper's main theorem and remains open.

Sources & referencesView supporting material

Primary source

Bartłomiej Zawalski, “On flat shadow boundaries from point light sources and the characterization of ellipsoids”, arXiv:2603.29130 (2026).

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.