The geometric fibration conjecture for reductive homogeneous spaces

Let G/HG/H be a reductive homogeneous space, with maximal compact subgroup KK and KH=KHK_H=K\cap H, and set X=K/KHX=K/K_H. Let Γ\Gamma be a torsion-free subgroup of GG acting properly discontinuously and cocompactly on G/HG/H. Then M=Γ\G/HM=\Gamma\backslash G/H is the associated compact quotient.

Geometric fibration conjecture. The group Γ\Gamma is the fundamental group of a closed aspherical manifold MM, and there exists a smooth Γ\Gamma-equivariant fiber bundle

G/HM~G/H\longrightarrow \widetilde{M}

whose fibers are GG-translates of XX, where M~\widetilde{M} is the universal cover of MM.

This conjecture predicts that compact quotients virtually fiber with fibers modeled on the maximal compact subspace. It is known in several examples, including certain group manifolds and SO(2n,2)/U(n,1)\operatorname{SO}(2n,2)/\operatorname{U}(n,1), but remains open in general.

Sources & referencesView supporting material

Primary source

Fanny Kassel, Yosuke Morita and Nicolas Tholozan, “Compact quotients of homogeneous spaces and homotopy theory of sphere bundles”, arXiv:2601.05857 (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.