The Space Form Conjecture

From papers

Let (p,q)(p,q) denote the signature of a pseudo-Riemannian manifold, with p,qp,q as in the displayed classification table.

Space Form Conjecture. There exists a compact, complete pseudo-Riemannian manifold of signature (p,q)(p,q) with constant sectional curvature 11 if and only if (p,q)(p,q) lies in the following list:

pN0137q0N2N4N8\begin{array}{c|ccccc} p&\mathbb{N}&0&1&3&7\\ q&0&\mathbb{N}&2\mathbb{N}&4\mathbb{N}&8 \end{array}

This is presented as a special case of the standard quotient conjecture. The supplied text gives no resolution status.

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Sources & referencesView supporting material

Primary source

Toshiyuki Kobayashi, “Proper Actions and Representation Theory”, arXiv:2506.15616 (2025).

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