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Countable products of metrics is metrizable #763

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merged 14 commits into from
Feb 7, 2023

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@zstone1 zstone1 commented Oct 7, 2022

Motivation for this change

Finally, we prove that countable products of metrics are metrizable! In particularly, the cantor set is metrizable. I have

  • A definition for countable_uniformity. Several lemmas use it, so it made sense to factor into a nicer definition. Note that this property is equivalent to metrizability, so it has little purpose outside of this family of proofs.
  • The main proof is that countable products preserve countable_uniformity. The definition of sup entourages is kinda annoying, so the proof is on the large side. It's not a blocker, just an inconvenience.
  • A bunch of definitions to build mixins and types.
Things done/to do
  • added corresponding entries in CHANGELOG_UNRELEASED.md
    (do not edit former entries, only append new ones, be careful:
    merge and rebase have a tendency to mess up CHANGELOG_UNRELEASED.md)
  • added corresponding documentation in the headers
Automatic note to reviewers

Read this Checklist and put a milestone if possible.

@zstone1 zstone1 changed the title Countable ent Countable products of metrcs is metrizable Oct 7, 2022
This was referenced Oct 10, 2022
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zstone1 commented Jan 2, 2023

Is there anything else required to merge this, or is this ready for an approval?

@affeldt-aist affeldt-aist changed the title Countable products of metrcs is metrizable Countable products of metrics is metrizable Jan 18, 2023
@affeldt-aist affeldt-aist added this to the 0.6.1 milestone Feb 6, 2023
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I tried to improve a bit the scripts. I noticed uses of projT1/projT2 where proj1_sig a.k.a. as sval would have been in order (causing at least one useless manual conversion) but it appears that using sval makes it for unfolded expressions. I think that the definition of sval is at fault and PRed MathComp math-comp/math-comp#964 . We can maybe replace these expressions later.

@zstone1 zstone1 merged commit cabe781 into math-comp:master Feb 7, 2023
hoheinzollern pushed a commit to hoheinzollern/analysis that referenced this pull request Mar 9, 2023
* proving sups preserve countable ent

* proof going through

* unused proofs

* linting

* metric implies countable uniformity

* fixing changelog

* linting

* metric for products

* linting

* fixing docs

* use %:pos

* fixing changelog

* fix changelog

* nitpicking

---------

Co-authored-by: Reynald Affeldt <reynald.affeldt@aist.go.jp>
proux01 pushed a commit that referenced this pull request Mar 24, 2023
* proving sups preserve countable ent

* proof going through

* unused proofs

* linting

* metric implies countable uniformity

* fixing changelog

* linting

* metric for products

* linting

* fixing docs

* use %:pos

* fixing changelog

* fix changelog

* nitpicking

---------

Co-authored-by: Reynald Affeldt <reynald.affeldt@aist.go.jp>
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2 participants