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Geodesic completeness of the affine connection on compact integral-integral affine bases

Determine whether the torsion-free flat affine connection induced by an integral-integral affine atlas on a compact manifold—specifically the compact base B of a Lagrangian torus fibration with integral-integral affine structure—is geodesically complete.

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Background

In developing their Downstairs Theorem relating volume to lattice points on integral-integral affine manifolds, the authors consider the base B of a Lagrangian torus fibration, which acquires an integral-integral affine structure.

Despite B being compact, the authors point out that the geodesic completeness of the induced affine connection is unknown. They identify this as a special case of the Markus conjecture, which concerns completeness for closed affine manifolds whose transition maps have determinant ±1.

References

One thing that makes the Downstairs Theorem interesting is that, although the base B is compact, we do not know if its affine connection is geodesically complete. This is a special case of the Markus conjecture; see §\ref{sec:downstairs}.

Integral-integral affine geometry, geometric quantization, and Riemann-Roch (2411.10348 - Hamilton et al., 15 Nov 2024) in Introduction