fibered product

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• Tensor product of modules — In mathematics, the tensor product of modules is a construction that allows arguments about bilinear maps (roughly speaking, multiplication ) to be carried out in terms of linear maps (module homomorphisms). The module construction is analogous… …   Wikipedia

• Grothendieck topology — In category theory, a branch of mathematics, a Grothendieck topology is a structure on a category C which makes the objects of C act like the open sets of a topological space. A category together with a choice of Grothendieck topology is called a …   Wikipedia

• Pullback (category theory) — In category theory, a branch of mathematics, a pullback (also called a fibered product or Cartesian square) is the limit of a diagram consisting of two morphisms f : X → Z and g : Y → Z with a common codomain. The pullback is often written: P = X …   Wikipedia

• Subfunctor — In category theory, a branch of mathematics, a subfunctor is a special type of functor which is an analogue of a subset. Definition Let C be a category, and let F be a functor from C to the category Set of all sets. A functor G from C to Set is a …   Wikipedia

• Sieve (category theory) — In category theory, a branch of mathematics, a sieve is a way of choosing arrows with a common codomain. It is a categorical analogue of a collection of open subsets of a fixed open set in topology. In a Grothendieck topology, certain sieves… …   Wikipedia

• Seifert 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… …   Wikipedia

• JSJ decomposition — In mathematics, the JSJ decomposition, also known as the toral decomposition, is a topological construct given by the following theorem: Irreducible orientable closed (i.e., compact and without boundary) 3 manifolds have a unique (up to isotopy)… …   Wikipedia

• Pushout (category theory) — In category theory, a branch of mathematics, a pushout (also called a fibered coproduct or fibered sum or cocartesian square or amalgamed sum) is the colimit of a diagram consisting of two morphisms f : Z → X and g : Z → Y with a common …   Wikipedia

• Algebraic stack — In algebraic geometry, an algebraic stack is a concept introduced to generalize algebraic varieties, schemes, and algebraic spaces. They were originally proposed in a 1969 paper[1] by Pierre Deligne and David Mumford to define the (fine) moduli… …   Wikipedia

• Bass–Serre theory — is a part of the mathematical subject of group theory that deals with analyzing the algebraic structure of groups acting by automorphisms on simplicial trees. The theory relates group actions on trees with decomposing groups as iterated… …   Wikipedia

• Geometrization conjecture — Thurston s geometrization conjecture states that compact 3 manifolds can be decomposed canonically into submanifolds that have geometric structures. The geometrization conjecture is an analogue for 3 manifolds of the uniformization theorem for… …   Wikipedia