nil homeomorphism
1Seifert fiber space — A Seifert fiber space is a 3 manifold together with a nice decomposition as a disjoint union of circles. In other words it is a S^1 bundle (circle bundle) over a 2 dimensional orbifold. Most small 3 manifolds are Seifert fiber spaces, and they… …
2Fibré de Seifert — En topologie, un fibré de Seifert est une variété de dimension 3 munie d une « bonne » partition en cercles. Plus précisément, c est un fibré en cercles sur un orbifold de dimension 2. Ces variétés ont été introduites par Herbert… …
3Monoid — This article is about the mathematical concept. For the alien creatures in the Doctor Who adventure, see The Ark (Doctor Who). Coherence law for monoid unit In abstract algebra, a branch of mathematics, a monoid is an algebraic structure with a… …
4Torus bundle — In mathematics, in the sub field of geometric topology, a torus bundle is a kind of surface bundle over the circle, which in turn are a class of three manifolds.ConstructionTo obtain a torus bundle: let f be an orientation preserving… …
