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equalizer_._category_theory [2016/05/19 19:53] nikolaj |
equalizer_._category_theory [2016/05/21 18:26] nikolaj |
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+ | {{ category_theory_equalizer_diagram.png?X200}} | ||
=== Examples === | === Examples === | ||
- | In ${\bf{Set}}$, if $f,g:A\to B$, then their equalizer $E$ is the set $\{a\in A\ |\ f(a)=g(a)\}$ and $e:E\to A$ is the obvious injection. | + | In ${\bf{Set}}$, if $f,g:A\to B$, then their equalizer is the set |
+ | $E=\{a\in A\ |\ f(a)=g(a)\}$ | ||
+ | |||
+ | and $e:E\to A$ is the obvious injection. | ||
+ | |||
+ | Remark: In the image, $e=E$ and $i=e$. | ||
=== Reference === | === Reference === | ||
nLab: [[http://ncatlab.org/nlab/show/equalizer|Equalizer]] | nLab: [[http://ncatlab.org/nlab/show/equalizer|Equalizer]] | ||
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=== Context === | === Context === | ||
[[Functor]] | [[Functor]] | ||
- | === Refinement of === | + | === Subset of === |
- | [[Limit . category theory]] | + | [[A triangle limit]] |