Freyd adjoint functor theorem
E621114
The Freyd adjoint functor theorem is a fundamental result in category theory that provides general conditions under which a functor admits a left or right adjoint, linking completeness and solution-set conditions to the existence of adjoint functors.
Statements (44)
| Predicate | Object |
|---|---|
| instanceOf | mathematical theorem ⓘ |
| appearsIn | Peter Freyd’s work on abelian categories ⓘ |
| appliesTo |
functors preserving colimits
ⓘ
functors preserving limits ⓘ |
| concerns |
adjoint functors
ⓘ
existence of left adjoints ⓘ existence of right adjoints ⓘ functors between categories ⓘ |
| field | category theory ⓘ |
| givesConditionFor |
existence of left adjoint functor
ⓘ
existence of right adjoint functor ⓘ |
| hasVariant |
general adjoint functor theorem
NERFINISHED
ⓘ
special adjoint functor theorem ⓘ |
| implies | existence of adjoints under completeness and solution set conditions ⓘ |
| importance | fundamental existence theorem for adjoints in category theory ⓘ |
| isToolFor |
constructing adjoint functors
ⓘ
proving existence of free objects ⓘ proving existence of limits and colimits via adjoints ⓘ |
| namedAfter | Peter Freyd NERFINISHED ⓘ |
| relatedTo |
Brown representability theorem
NERFINISHED
ⓘ
Yoneda lemma NERFINISHED ⓘ adjunction between categories ⓘ |
| relatesConcept |
cocomplete categories
ⓘ
complete categories ⓘ completeness of categories ⓘ locally small categories ⓘ smallness conditions ⓘ solution set condition ⓘ |
| standardReference |
Peter Freyd – Abelian Categories
NERFINISHED
ⓘ
Saunders Mac Lane – Categories for the Working Mathematician NERFINISHED ⓘ |
| typicalConclusion |
functor has a left adjoint
ⓘ
functor has a right adjoint ⓘ |
| typicalHypothesis |
domain category is complete
ⓘ
functor preserves limits ⓘ solution set condition holds ⓘ |
| usedIn |
algebra
ⓘ
higher category theory ⓘ homological algebra ⓘ topology ⓘ |
| usesConcept |
comma categories
ⓘ
initial objects ⓘ representable functors ⓘ terminal objects ⓘ universal morphisms ⓘ |
Referenced by (2)
Full triples — surface form annotated when it differs from this entity's canonical label.