Category of elements

Category of elements

In category theory, for every presheaf P inhat C := mathbf{Set}^{C^{op the category of elements mathbf{El}(P) of P is the category defined as follows:
* its objects are pairs (A,a) where A is an object of C and ain P(A),
* its morphisms (A,a) o (B,b) are the morphisms f:A o B of C such that a=P(f)(b).

This construction can be extended into a functor mathbf{El} from hat C to mathbf{Cat}, the category of small categories.


Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • elements — n. Forces of nature such as rain and snow. The Essential Law Dictionary. Sphinx Publishing, An imprint of Sourcebooks, Inc. Amy Hackney Blackwell. 2008. elements The component parts of a legal claim or cause of action. T …   Law dictionary

  • elements of a case — The component parts of a legal claim or cause of action. To win a lawsuit, a plaintiff must prove every element of a legal claim. For example, here are the elements of a breach of contract claim: * There was a valid contract. * The plaintiff… …   Law dictionary

  • Elements of Life — Studio album by Tiësto Released 6 April 2007 …   Wikipedia

  • elements of a crime — The component parts of crimes. For example, robbery is defined as the taking and carrying away of property of another by force or fear with the intent to permanently deprive the owner of the property. Each of those four parts is an element that… …   Law dictionary

  • Category of groups — In mathematics, the category Grp has the class of all groups for objects and group homomorphisms for morphisms. As such, it is a concrete category. The study of this category is known as group theory.The monomorphisms in Grp are precisely the… …   Wikipedia

  • Category of sets — In mathematics, the category of sets, denoted as Set, is the category whose objects are all sets and whose morphisms are all functions. It is the most basic and the most commonly used category in mathematics.Properties of the category of setsThe… …   Wikipedia

  • Category theory — In mathematics, category theory deals in an abstract way with mathematical structures and relationships between them: it abstracts from sets and functions to objects and morphisms . Categories now appear in most branches of mathematics and in… …   Wikipedia

  • Category (mathematics) — In mathematics, a category is an algebraic structure that comprises objects that are linked by arrows . A category has two basic properties: the ability to compose the arrows associatively and the existence of an identity arrow for each object. A …   Wikipedia

  • Category of rings — In mathematics, the category of rings, denoted by Ring, is the category whose objects are rings (with identity) and whose morphisms are ring homomorphisms (preserving the identity). Like many categories in mathematics, the category of rings is… …   Wikipedia

  • Éléments de géométrie algébrique — Infobox Book name = Éléments de géométrie algébrique author = Alexander Grothendieck and Jean Dieudonné language = French subject = Algebraic geometry publisher = Institut des Hautes Études Scientifiques pub date = 1960 ndash;1967The Éléments de… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”