Exactness of six-term exact sequence of Ext at first spot #1738
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
jdchristensen
approved these changes
May 2, 2023
Alizter
reviewed
May 2, 2023
Alizter
approved these changes
May 2, 2023
|
@jarlg LGTM, shall I merge? |
|
Great! Yes, go ahead. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
We prove
isexact_abses_sixterm_i, which is exactness at the first spot of the six-term exact sequence of Ext groups associated to a short exact sequence. It's an incarnation of precomposition by a surjection is an injection, so we state and prove that first.The statement was included without a proof (using
Abort.) in a previous PR.