Limits and colimits

Limits and colimits as adjoints to the diagonal

Let ๐–ข,๐–ฉ be categories with ๐–ฉ small, and consider the diagonal functor

ฮ”๐–ฉ:๐–ขโ†’๐–ข๐–ฉ

from ๐–ข to its category of diagrams. Then the left and right adjoints of ฮ”๐–ฉ, if they exist are given by colimits and limits respectively.1

limโŸถ๐–ฉโŠฃฮ”๐–ฉโŠฃlimโŸต๐–ฉ
Proof

#missing/proof


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Footnotes

  1. 2010. Category theory, ยง9.3, pp. 217โ€“218. โ†ฉ