A classification conjecture for homotopy Hopf manifolds failing the one-twelfth invariant

From papers

Let σ8\sigma^8 be the space of homotopy Hopf manifolds, let σ~\widetilde{\sigma} be the map appearing in the source, and let θ7\theta^7 denote the group of homotopy seven-spheres. A homotopy Hopf manifold is said to fail the one-twelfth association when it cannot be associated with the number 112\frac{1}{12} in the Fourier expansion of the \wp-Weierstrass function. Classification conjecture. Given Xσ8X\in\sigma^8, if XX fails the one-twelfth association, then either

  1. XX is the image under σ~\widetilde{\sigma} of an element (m,1m,l)π3(SO(3))π3(SO(3))π1(SO(2))(m,1-m,l)\in\pi_3(\mathrm{SO}(3))\otimes\pi_3(\mathrm{SO}(3))\otimes\pi_1(\mathrm{SO}(2)) with l1l\neq 1; or
  2. X=Σ7×S1X=\Sigma^7\times\mathrm{S}^1 for some Σ7θ7\Sigma^7\in\theta^7 that admits no realization as the total space of an S3\mathrm{S}^3-bundle over S4\mathrm{S}^4, equivalently, Σ7\Sigma^7 is not the total space of a Milnor bundle.

The claim is presented as a proposed classification of the exceptions to the numerical assignment by separating nontrivial twisting data from products involving homotopy seven-spheres that are not Milnor-bundle total spaces. The supplied text gives no evidence of resolution.

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Sources & referencesView supporting material

Primary source

Leonardo F. Cavenaghi, Lino Grama and Ludmil Katzarkov, “A Geometric Realization of Spherical T-Duality via -Diagrams”, arXiv:2404.19088 (2026).

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