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[Merged by Bors] - feat(ring_theory): definition and properties of relative ideal norm #18299

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@Vierkantor Vierkantor commented Jan 26, 2023

This PR provides a definition of the relative ideal norm ideal.span_norm R I as the ideal spanned by the norms of elements in I. We also give some basic results on this definition. A follow-up PR will bundle this into a homomorphism ideal.rel_norm.


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@Vierkantor Vierkantor added awaiting-review The author would like community review of the PR blocked-by-other-PR This PR depends on another PR which is still in the queue. A bot manages this label via PR comment. awaiting-CI The author would like to see what CI has to say before doing more work. t-algebra Algebra (groups, rings, fields etc) t-number-theory Number theory (also use t-algebra or t-analysis to specialize) labels Jan 26, 2023
@github-actions github-actions bot removed the awaiting-CI The author would like to see what CI has to say before doing more work. label Jan 26, 2023
@mathlib-dependent-issues-bot mathlib-dependent-issues-bot removed the blocked-by-other-PR This PR depends on another PR which is still in the queue. A bot manages this label via PR comment. label Jan 27, 2023
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@alreadydone alreadydone added awaiting-author A reviewer has asked the author a question or requested changes merge-conflict Please `git merge origin/master` then a bot will remove this label. and removed awaiting-review The author would like community review of the PR labels Jan 30, 2023
This PR provides a definition of the relative ideal norm `ideal.span_norm R I` as the ideal spanned by the norms of elements in `I`. We also give some basic results on this definition. A follow-up PR will bundle this into a homomorphism `ideal.rel_norm`.
@Vierkantor Vierkantor added awaiting-review The author would like community review of the PR and removed awaiting-author A reviewer has asked the author a question or requested changes merge-conflict Please `git merge origin/master` then a bot will remove this label. labels Jan 30, 2023
@riccardobrasca riccardobrasca self-assigned this Jan 31, 2023
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Thanks!

bors d+

src/ring_theory/ideal/norm.lean Outdated Show resolved Hide resolved
def span_norm (I : ideal S) : ideal R :=
ideal.span (algebra.norm R '' (I : set S))

@[simp] lemma span_norm_bot
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This is false without nontrivial S, right?

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Yes, then this would be ideal.span {algebra.norm 1} = ideal.span {1} = ⊤ (since norm/det breaks the tie between 0 = 1 in favour of 1).

src/ring_theory/ideal/norm.lean Outdated Show resolved Hide resolved
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bors bot commented Jan 31, 2023

✌️ Vierkantor can now approve this pull request. To approve and merge a pull request, simply reply with bors r+. More detailed instructions are available here.

@leanprover-community-bot-assistant leanprover-community-bot-assistant added delegated The PR author may merge after reviewing final suggestions. and removed awaiting-review The author would like community review of the PR labels Jan 31, 2023
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bors merge

@github-actions github-actions bot added the ready-to-merge All that is left is for bors to build and merge this PR. (Remember you need to say `bors r+`.) label Jan 31, 2023
bors bot pushed a commit that referenced this pull request Jan 31, 2023
…18299)

This PR provides a definition of the relative ideal norm `ideal.span_norm R I` as the ideal spanned by the norms of elements in `I`. We also give some basic results on this definition. A follow-up PR will bundle this into a homomorphism `ideal.rel_norm`.
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Pull request successfully merged into master.

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@bors bors bot changed the title feat(ring_theory): definition and properties of relative ideal norm [Merged by Bors] - feat(ring_theory): definition and properties of relative ideal norm Jan 31, 2023
@bors bors bot closed this Jan 31, 2023
@bors bors bot deleted the ideal-span-norm-def branch January 31, 2023 19:36
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