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derived ImageEmbedding as the colift along the coastriction to image

Open mohamed-barakat opened this issue 2 years ago • 7 comments

mohamed-barakat avatar Oct 17 '23 16:10 mohamed-barakat

Codecov Report

Attention: 6 lines in your changes are missing coverage. Please review.

Files Coverage Δ
CAP/PackageInfo.g 100.00% <100.00%> (ø)
CAP/gap/DerivedMethods.autogen.gi 86.93% <88.88%> (+0.03%) :arrow_up:
CAP/gap/DerivedMethods.gi 84.00% <71.42%> (-0.11%) :arrow_down:

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codecov[bot] avatar Oct 17 '23 17:10 codecov[bot]

Please also add a WithGiven version of the derivation to make it consistent with the analogous derivations of CoastrictionToImage(WithGiven...).

zickgraf avatar Oct 26 '23 09:10 zickgraf

I just noticed that CAP's definition of Image does not require the coastriction to the image to be epi. Hence, in general this derivation is not valid, or am I missing something?

zickgraf avatar Oct 26 '23 09:10 zickgraf

I just noticed that CAP's definition of Image does not require the coastriction to the image to be epi. Hence, in general this derivation is not valid, or am I missing something?

You are right, I have to use the general lift an colift.

mohamed-barakat avatar Oct 26 '23 10:10 mohamed-barakat

You are right, I have to use the general lift an colift.

Such a factorization is always unique up to unique isomorphism.

mohamed-barakat avatar Oct 26 '23 10:10 mohamed-barakat

It is now unclear to me why the colift is necessarily a monomorphism.

mohamed-barakat avatar Oct 26 '23 10:10 mohamed-barakat

I restricted the derivation to IsAbelianCategory. I remember that the natural morphism from the coimage to image is both mono and epi, making these derivations also valid for IsPreAbelianCategory. I can relax the conditions in a later PR once I have a proof.

mohamed-barakat avatar Oct 26 '23 15:10 mohamed-barakat