injective extension

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• Injective hull — This article is about the injective hull of a module in algebra. For injective hulls of metric spaces, also called tight spans, injective envelopes, or hyperconvex hulls, see tight span. In mathematics, especially in the area of abstract algebra… …   Wikipedia

• Injective module — In mathematics, especially in the area of abstract algebra known as module theory, an injective module is a module Q that shares certain desirable properties with the Z module Q of all rational numbers. Specifically, if Q is a submodule of some… …   Wikipedia

• Extension radicielle — Dans la théorie des extensions de corps, à l opposé des extensions algébriques séparables, il existe les extensions radicielles. C est un phénomène spécifique à la caractéristique positive et qui apparaît naturellement avec les corps de fonctions …   Wikipédia en Français

• Injective cogenerator — In category theory, the concept of an injective cogenerator is drawn from examples such as Pontryagin duality. Generators are objects which cover other objects as an approximation, and (dually) cogenerators are objects which envelope other… …   Wikipedia

• Field extension — In abstract algebra, field extensions are the main object of study in field theory. The general idea is to start with a base field and construct in some manner a larger field which contains the base field and satisfies additional properties. For… …   Wikipedia

• Essential extension — In mathematics, specifically module theory, given a ring R and R modules :Msubseteq E, the module E is an essential extension if for every nonzero submodule :Nsubseteq E, we have:Ncap M e 0. Also, M is then said to be an essential submodule of E …   Wikipedia

• HNN extension — In mathematics, the HNN extension is a basic construction of combinatorial group theory.Introduced in a 1949 paper Embedding Theorems for Groups [ cite journal|title=Embedding Theorems for Groups|journal=Jornal of the London Mathematical… …   Wikipedia

• Friedrichs extension — In functional analysis, the Friedrichs extension is a canonical self adjoint extension of a non negative densely defined symmetric operator. It is named after the mathematician Kurt Friedrichs. This extension is particularly useful in situations… …   Wikipedia

• Ore extension — In mathematics, especially in the area of algebra known as ring theory, an Ore extension, named after Oystein Ore, is a special type of a ring extension whose properties are relatively well understood. Ore extensions appear in several natural… …   Wikipedia

• Twelvefold way — In combinatorics, the twelvefold way is a name given to a systematic classification of 12 related enumerative problems concerning two finite sets, which include the classical problems of counting permutations, combinations, multisets, and… …   Wikipedia

• LINÉAIRE ET MULTILINÉAIRE (ALGÈBRE) — LINЙAIRE ET MULTILINЙAIRE (ALGИBRE) L’algèbre linéaire sur un corps commutatif, telle qu’on la trouvera présentée ici, s’est progressivement dégagée, au cours du XIXe siècle et au début du XXe, de la théorie des équations linéaires (systèmes de n …   Encyclopédie Universelle