e/Zoll surface

Information
has gloss	eng: A Zoll surface is a surface homeomorphic to the 2-sphere, equipped with a Riemannian metric all of whose geodesics are closed and of equal length. While the usual unit-sphere metric on S2 obviously has this property, it also has an infinite-dimensional family of geometrically distinct deformations which are still Zoll. In particular, most Zoll surfaces do not have constant curvature.
lexicalization	eng: Zoll surface
instance of	e/Surface