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feat(topology/algebra/infinite_sum): dot notation, cauchy sequences #2171

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merged 5 commits into from Mar 18, 2020

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sgouezel
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Cleanup of the file infinite_sum.lean, adding what I will need to define analytic functions in a later PR. Two main things:

  • Use the dot notation everywhere (with has_sum.add, has_sum.summable, summable.has_sum and so on)
  • Develop the relationship between the convergence of a sum and the fact that s -> s.sum f is a Cauchy sequence when the finset s tends to at_top.

Plus many minor missing lemmas scattered all over the place.

@sgouezel sgouezel added the awaiting-review The author would like community review of the PR label Mar 17, 2020

lemma tsum_eq_has_sum (ha : has_sum f a) : (∑b, f b) = a := has_sum_unique (has_sum_tsum ⟨a, ha⟩) ha
lemma tsum_eq_has_sum (ha : has_sum f a) : (∑b, f b) = a :=
has_sum_unique (summable.has_sum ⟨a, ha⟩) ha

lemma has_sum_iff_of_summable (h : summable f) : has_sum f a ↔ (∑b, f b) = a :=
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summable.has_sum_iff?

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This has prompted me to check the file again, and I have found two or three other lemmas that could benefit from the dot notation. Done.

@urkud
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urkud commented Mar 18, 2020

A few minor comments, otherwise LGTM.

@urkud urkud added awaiting-author A reviewer has asked the author a question or requested changes and removed awaiting-review The author would like community review of the PR labels Mar 18, 2020
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Thanks for your comments!

@sgouezel sgouezel 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 labels Mar 18, 2020
@urkud urkud added ready-to-merge All that is left is for bors to build and merge this PR. (Remember you need to say `bors r+`.) and removed awaiting-review The author would like community review of the PR labels Mar 18, 2020
@mergify mergify bot merged commit 00d9f1d into master Mar 18, 2020
@mergify mergify bot deleted the sgouezel_summable branch March 18, 2020 23:52
cipher1024 pushed a commit that referenced this pull request Apr 20, 2020
…2171)

* more material on infinite sums

* minor fixes

* cleanup

* yury's comments

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
anrddh pushed a commit to anrddh/mathlib that referenced this pull request May 15, 2020
…eanprover-community#2171)

* more material on infinite sums

* minor fixes

* cleanup

* yury's comments

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
anrddh pushed a commit to anrddh/mathlib that referenced this pull request May 16, 2020
…eanprover-community#2171)

* more material on infinite sums

* minor fixes

* cleanup

* yury's comments

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
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2 participants