If a Hilbert geometry of twice differentiable boundary has two quadratic infinitesimal spheres, then the Hilbert geometry is a Cayley–Klein model of the hyperbolic geometry.

中文翻译：

---

具有黎曼点的希尔伯特几何

如果具有两次可微边界的希尔伯特几何具有两个二次无限小球，则希尔伯特几何就是双曲线几何的Cayley-Klein模型。