Conjecture on the real rank boundary of ternary quartics

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Let ff be a ternary quartic, let C(f)C(f) be its middle catalecticant, and let disc⁡(f)\operatorname{disc}(f) and Bdisc⁡(f)\operatorname{Bdisc}(f) denote respectively the discriminant and the Blekherman discriminant. Let ∂alg(R4)\partial_{\rm alg}(\mathcal{R}_4) be the algebraic real rank boundary in P14\mathbb{P}^{14}. Quartic real rank boundary conjecture. The boundary is a reducible hypersurface of degree

84=6+27+51,84=6+27+51,

with three irreducible components, and algebraically

∂alg(R4)=det⁡(C(f))⋅disc⁡(f)⋅Bdisc⁡(f).\partial_{\rm alg}(\mathcal{R}_4)=\operatorname{det}(C(f))\cdot\operatorname{disc}(f)\cdot\operatorname{Bdisc}(f).

This conjecture identifies the three expected boundary components: the catalecticant determinant, the discriminant, and the Blekherman discriminant. The source gives no resolution status.

References

Primary source

Mateusz Michałek, Hyunsuk Moon, Bernd Sturmfels and Emanuele Ventura, “Real Rank Geometry of Ternary Forms”, arXiv:1601.06574 (2016).

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