hom-sets (i.e. sets of morphisms between objects) give rise to important functors to the category of sets. These functors are called hom-functors and...
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the group homomorphism Hom(f, g): Hom(A2, B1) → Hom(A1, B2) is given by φ ↦ g ∘ φ ∘ f. See Hom functor. Representable functors We can generalize the previous...
24 KB (3,550 words) - 22:28, 25 April 2025
Yoneda lemma (redirect from Yoneda functor)
a hom-functor. This functor is denoted: h A ( − ) ≡ H o m ( A , − ) {\displaystyle h_{A}(-)\equiv \mathrm {Hom} (A,-)} . The (covariant) hom-functor h...
20 KB (3,448 words) - 09:53, 27 May 2025
tensor-hom adjunction is that the tensor product − ⊗ X {\displaystyle -\otimes X} and hom-functor Hom ( X , − ) {\displaystyle \operatorname {Hom} (X,-)}...
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Limit (category theory) (redirect from Continuous functor)
from the fact the covariant Hom functor Hom(N, –) : C → Set preserves all limits in C. By duality, the contravariant Hom functor must take colimits to limits...
27 KB (4,330 words) - 09:29, 26 May 2025
Quasi-category (redirect from Hom-functor for ∞-categories)
category generated by it. Since Hom S ′ {\displaystyle \operatorname {Hom} _{S'}} is a functor, ( x , y ) ↦ Sing | Hom C ( x , y ) | {\displaystyle...
22 KB (3,353 words) - 20:39, 1 June 2025
In mathematics, the Ext functors are the derived functors of the Hom functor. Along with the Tor functor, Ext is one of the core concepts of homological...
22 KB (4,026 words) - 13:12, 5 June 2025
of sets. For each object A of C let Hom(A,–) be the hom functor that maps object X to the set Hom(A,X). A functor F : C → Set is said to be representable...
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{\displaystyle \mathrm {hom} _{\mathcal {C}}(Fd,c)} , φ f {\displaystyle \varphi f} is the right adjunct of f {\displaystyle f} (p. 81). The functor F {\displaystyle...
64 KB (10,260 words) - 08:58, 28 May 2025
category theory, a faithful functor is a functor that is injective on hom-sets, and a full functor is surjective on hom-sets. A functor that has both properties...
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Presheaf (category theory) (category Functors)
the contravariant hom-functor Hom(–, A) for some object A of C is called a representable presheaf. Some authors refer to a functor F : C o p → V {\displaystyle...
8 KB (1,272 words) - 10:40, 28 April 2025
functor is called the internal Hom functor, and the object A ⇒ B {\displaystyle A\Rightarrow B} is called the internal Hom of A {\displaystyle A} and B...
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Sheaf (mathematics) (redirect from Sheaf hom)
direct image functor, taking sheaves and their morphisms on the domain to sheaves and morphisms on the codomain, and an inverse image functor operating in...
69 KB (11,082 words) - 02:10, 6 June 2025
specifically in the area of category theory, a forgetful functor (also known as a stripping functor) "forgets" or drops some or all of the input's structure...
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Closed category (redirect from Internal Hom object)
internal hom [x, y]. Every closed category has a forgetful functor to the category of sets, which in particular takes the internal hom to the external hom. A...
3 KB (348 words) - 12:41, 19 March 2025
Thus the contravariant hom-functor changes coproducts into products. Stated another way, the hom-functor, viewed as a functor from the opposite category...
12 KB (2,130 words) - 16:31, 3 May 2025
In mathematics, certain functors may be derived to obtain other functors closely related to the original ones. This operation, while fairly abstract, unifies...
18 KB (3,092 words) - 11:11, 24 December 2024
{\displaystyle \mathrm {Hom} (A\otimes B,C)\cong \mathrm {Hom} (A,B\Rightarrow C).} Here, Hom denotes the (external) Hom-functor of all morphisms in the...
36 KB (5,025 words) - 17:55, 29 March 2025
{\displaystyle F:\mathrm {Hom} _{\mathbf {Vect} }(T,U)\rightarrow \mathrm {Hom} _{\mathbf {Vect} }(F(T),F(U)),} where Hom is notation for Hom functor. If this map...
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exact functors are the Hom functors: if A is an abelian category and A is an object of A, then FA(X) = HomA(A,X) defines a covariant left-exact functor from...
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to make Rel a dagger category. The category has two functors into itself given by the hom functor: A binary relation R ⊆ A × B and its transpose RT ⊆...
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Enriched category (redirect from Enriched functor)
category, enriched functor, etc... reduce to the original definitions from ordinary category theory. An enriched category with hom-objects from monoidal...
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2-category (redirect from Lax functor)
objects a and b the hom-set Hom ( a , b ) {\displaystyle \operatorname {Hom} (a,b)} acquires a structure of a category as a functor category. A vertical...
19 KB (2,524 words) - 10:33, 29 April 2025
in C, the natural functor (evaluation at the identity) Hom _ ( h x , F ) → F ( x ) {\displaystyle {\underline {\operatorname {Hom} }}(h_{x},F)\to F(x)}...
8 KB (1,228 words) - 09:56, 27 May 2025
a branch of mathematics, a functor category D C {\displaystyle D^{C}} is a category where the objects are the functors F : C → D {\displaystyle F:C\to...
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Loop space (redirect from Loop functor)
computer science is currying, where the cartesian product is adjoint to the hom functor.) Informally this is referred to as Eckmann–Hilton duality. The loop...
5 KB (597 words) - 15:47, 26 May 2025
product and the Hom functor are adjoint; however, they might not always lift to an exact sequence. This leads to the definition of the Tor functor and the Ext...
5 KB (718 words) - 07:53, 18 February 2025
Category theory (section Functors)
we have ∘ : hom ( b , c ) × hom ( a , b ) ↦ hom ( a , c ) {\displaystyle \circ :{\text{hom}}(b,c)\times {\text{hom}}(a,b)\mapsto {\text{hom}}(a,c)} The...
34 KB (3,910 words) - 23:58, 6 June 2025
theory, monoidal functors are functors between monoidal categories which preserve the monoidal structure. More specifically, a monoidal functor between two...
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category, it is equivalent to require that the hom functor Hom C ( − , Q ) {\displaystyle \operatorname {Hom} _{\mathbf {C} }(-,Q)} carries monomorphisms...
8 KB (1,031 words) - 17:57, 2 September 2022