coequalizer of modules

1. Proposition

Let 20240122-coequalizer_of_modules_22a535293244fe74fc7a4bdd15d746de7c32685f.svg be a ring, 20240122-coequalizer_of_modules_8bf4eb9b75e039701faeb68f09475976f5677acf.svg be modules and 20240122-coequalizer_of_modules_7ff6ee7b2408474c904995f2df148c09cde9a7c2.svg module-homomorphism. Then the coequalizer is the quotient module

20240122-coequalizer_of_modules_72daedf447c2f20513da1a3a9a24ef2c7899a1ee.svg

with

20240122-coequalizer_of_modules_0ecd2a900c777ef291dc97ed71385bd681b0e013.svg

2. Proof

note that 20240122-coequalizer_of_modules_b71e53a5c189bd6b8a86f0ba771ad9cff3dd7ffa.svg is a module homomorphism (see: Set of module homomorphisms as abelian group) Hence the module 20240122-coequalizer_of_modules_3da6e37579377d3f94c46ca8a2f19841277d031b.svg is a welldefined module

2.1. commuting

Let 20240122-coequalizer_of_modules_f033e8bc0590490e41c5828e661cf6c892da1117.svg such that 20240122-coequalizer_of_modules_762b6514c21846393b71119173bc0300c789f3de.svg. Then

2.2. universal property

Let 20240122-coequalizer_of_modules_1bfe7e289f13ae9ab51118624e48fbf3aefcf40d.svg be another module and 20240122-coequalizer_of_modules_77df9841c4d71ab3edd74424dd050fa09a8fef7d.svg

20240122-coequalizer_of_modules_a27709cafad4f74f0306addafa1dcd9914137fb4.svg

making this a cofork Then it follows, that

20240122-coequalizer_of_modules_b8c9c19481a05286830b09b64a83193969f24ac9.svg

or

20240122-coequalizer_of_modules_812e61d95f79ed4c9b43e13848fdf2466ac76839.svg

Thus 20240122-coequalizer_of_modules_16cc31348c3f80f01f2e901b53a39da6ff66367d.svg and by fundamental theorem of module homomorphisms, there exists a unique morphism 20240122-coequalizer_of_modules_72c77ca705ee8b12d798d106ca596b51a5b0eee8.svg

20240122-coequalizer_of_modules_6cf0ab0fb3d90731b4ee90bb50634bcebe6e1a04.svg

Date: nil

Author: Anton Zakrewski

Created: 2024-10-20 So 09:01