Helly-type intersection conjecture for projection-direction sets

Let F\mathcal{F} be an intersecting family of convex sets in R3\mathbb{R}^3. For each triple T={F1,F2,F3}(F3)T=\{F_1,F_2,F_3\}\in {\mathcal{F}\choose 3}, let DTS2D_T\subset S^2 consist of the directions a\mathbf{a} for which the orthogonal projections of F1,F2,F3F_1,F_2,F_3 onto the plane xa=0x\cdot\mathbf{a}=0 have a common point. Intersection conjecture for the sets DTD_T. For any three triples T1,T2,T3T_1,T_2,T_3, one has

DT1DT2DT3.D_{T_1}\cap D_{T_2}\cap D_{T_3}\neq\emptyset.

Together with the surrounding proposed lemmas, this would help prove that a line pierces cFc|\mathcal{F}| members of F\mathcal{F} for some constant cc. The supplied text does not state whether the assertion is resolved.

Sources & referencesView supporting material

Primary source

Daniel McGinnis and Shira Zerbib, “Line transversals in families of connected sets the plane”, arXiv:2103.05565 (2021).

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