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[Merged by Bors] - refactor(MeasureTheory): redefine on measures #10714

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@urkud urkud commented Feb 19, 2024

Redefine on MeasureTheory.Measure
so that μ ≤ ν ↔ ∀ s, μ s ≤ ν s by definition
instead of ∀ s, MeasurableSet s → μ s ≤ ν s.

Reasons

  • this way it is defeq to on outer measures;
  • if we decide to introduce an order on all DFunLike types
    and migrate measures to FunLike, then this is unavoidable;
  • the reasoning for the old definition was
    "it's slightly easier to prove μ ≤ ν this way";
    the counter-argument is
    "it's slightly harder to apply μ ≤ ν this way".

Other changes

  • golf some proofs broken by this change;
  • add @[gcongr] tags to some ENNReal lemmas;
  • fix the name
    ENNReal.coe_lt_coe_of_le -> ENNReal.ENNReal.coe_lt_coe_of_lt;
  • drop an unneeded MeasurableSet assumption
    in set_lintegral_pdf_le_map

Open in Gitpod

Redefine `≤` on `MeasureTheory.Measure`
so that `μ ≤ ν ↔ ∀ s, μ s ≤ ν s` by definition
instead of `∀ s, MeasurableSet s → μ s ≤ ν s`.

The reasons are:

- this way it is defeq to `≤` on outer measures;
- if we decide to introduce an order on all `DFunLike` types
  **and** migrate measures to `FunLike`, then this is unavoidable;
- the reasoning for the old definition was
  "it's slightly easier to prove `μ ≤ ν` this way";
  the counter-argument is
  "it's slightly harder to apply `μ ≤ ν` this way".

Other changes

- golf some proofs broken by this change;
- add `@[gcongr]` tags to some `ENNReal` lemmas;
- fix the name
  `ENNReal.coe_lt_coe_of_le` -> `ENNReal.ENNReal.coe_lt_coe_of_lt`;
- drop an unneeded `MeasurableSet` assumption
  in `set_lintegral_pdf_le_map`
@urkud urkud added awaiting-review The author would like community review of the PR t-measure-probability Measure theory / Probability theory labels Feb 19, 2024
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LGTM

Thanks!

bors merge

@@ -79,6 +79,7 @@ theorem toReal_le_toReal (ha : a ≠ ∞) (hb : b ≠ ∞) : a.toReal ≤ b.toRe
norm_cast
#align ennreal.to_real_le_to_real ENNReal.toReal_le_toReal

@[gcongr]
theorem toReal_mono (hb : b ≠ ∞) (h : a ≤ b) : a.toReal ≤ b.toReal :=
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unrelated to this PR: we should move finiteness to mathlib and add it as a gcongr discharger.

@leanprover-community-mathlib4-bot leanprover-community-mathlib4-bot added ready-to-merge This PR has been sent to bors. and removed awaiting-review The author would like community review of the PR labels Feb 21, 2024
mathlib-bors bot pushed a commit that referenced this pull request Feb 21, 2024
Redefine `≤` on `MeasureTheory.Measure`
so that `μ ≤ ν ↔ ∀ s, μ s ≤ ν s` by definition
instead of `∀ s, MeasurableSet s → μ s ≤ ν s`.

### Reasons

- this way it is defeq to `≤` on outer measures;
- if we decide to introduce an order on all `DFunLike` types
  **and** migrate measures to `FunLike`, then this is unavoidable;
- the reasoning for the old definition was
  "it's slightly easier to prove `μ ≤ ν` this way";
  the counter-argument is
  "it's slightly harder to apply `μ ≤ ν` this way".

### Other changes

- golf some proofs broken by this change;
- add `@[gcongr]` tags to some `ENNReal` lemmas;
- fix the name
  `ENNReal.coe_lt_coe_of_le` -> `ENNReal.ENNReal.coe_lt_coe_of_lt`;
- drop an unneeded `MeasurableSet` assumption
  in `set_lintegral_pdf_le_map`
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mathlib-bors bot commented Feb 21, 2024

This PR was included in a batch that was canceled, it will be automatically retried

mathlib-bors bot pushed a commit that referenced this pull request Feb 21, 2024
Redefine `≤` on `MeasureTheory.Measure`
so that `μ ≤ ν ↔ ∀ s, μ s ≤ ν s` by definition
instead of `∀ s, MeasurableSet s → μ s ≤ ν s`.

### Reasons

- this way it is defeq to `≤` on outer measures;
- if we decide to introduce an order on all `DFunLike` types
  **and** migrate measures to `FunLike`, then this is unavoidable;
- the reasoning for the old definition was
  "it's slightly easier to prove `μ ≤ ν` this way";
  the counter-argument is
  "it's slightly harder to apply `μ ≤ ν` this way".

### Other changes

- golf some proofs broken by this change;
- add `@[gcongr]` tags to some `ENNReal` lemmas;
- fix the name
  `ENNReal.coe_lt_coe_of_le` -> `ENNReal.ENNReal.coe_lt_coe_of_lt`;
- drop an unneeded `MeasurableSet` assumption
  in `set_lintegral_pdf_le_map`
@mathlib-bors
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mathlib-bors bot commented Feb 21, 2024

Pull request successfully merged into master.

Build succeeded:

@mathlib-bors mathlib-bors bot changed the title refactor(MeasureTheory): redefine on measures [Merged by Bors] - refactor(MeasureTheory): redefine on measures Feb 21, 2024
@mathlib-bors mathlib-bors bot closed this Feb 21, 2024
@mathlib-bors mathlib-bors bot deleted the YK-meas-le branch February 21, 2024 17:43
thorimur pushed a commit that referenced this pull request Feb 24, 2024
Redefine `≤` on `MeasureTheory.Measure`
so that `μ ≤ ν ↔ ∀ s, μ s ≤ ν s` by definition
instead of `∀ s, MeasurableSet s → μ s ≤ ν s`.

### Reasons

- this way it is defeq to `≤` on outer measures;
- if we decide to introduce an order on all `DFunLike` types
  **and** migrate measures to `FunLike`, then this is unavoidable;
- the reasoning for the old definition was
  "it's slightly easier to prove `μ ≤ ν` this way";
  the counter-argument is
  "it's slightly harder to apply `μ ≤ ν` this way".

### Other changes

- golf some proofs broken by this change;
- add `@[gcongr]` tags to some `ENNReal` lemmas;
- fix the name
  `ENNReal.coe_lt_coe_of_le` -> `ENNReal.ENNReal.coe_lt_coe_of_lt`;
- drop an unneeded `MeasurableSet` assumption
  in `set_lintegral_pdf_le_map`
thorimur pushed a commit that referenced this pull request Feb 26, 2024
Redefine `≤` on `MeasureTheory.Measure`
so that `μ ≤ ν ↔ ∀ s, μ s ≤ ν s` by definition
instead of `∀ s, MeasurableSet s → μ s ≤ ν s`.

### Reasons

- this way it is defeq to `≤` on outer measures;
- if we decide to introduce an order on all `DFunLike` types
  **and** migrate measures to `FunLike`, then this is unavoidable;
- the reasoning for the old definition was
  "it's slightly easier to prove `μ ≤ ν` this way";
  the counter-argument is
  "it's slightly harder to apply `μ ≤ ν` this way".

### Other changes

- golf some proofs broken by this change;
- add `@[gcongr]` tags to some `ENNReal` lemmas;
- fix the name
  `ENNReal.coe_lt_coe_of_le` -> `ENNReal.ENNReal.coe_lt_coe_of_lt`;
- drop an unneeded `MeasurableSet` assumption
  in `set_lintegral_pdf_le_map`
riccardobrasca pushed a commit that referenced this pull request Mar 1, 2024
Redefine `≤` on `MeasureTheory.Measure`
so that `μ ≤ ν ↔ ∀ s, μ s ≤ ν s` by definition
instead of `∀ s, MeasurableSet s → μ s ≤ ν s`.

### Reasons

- this way it is defeq to `≤` on outer measures;
- if we decide to introduce an order on all `DFunLike` types
  **and** migrate measures to `FunLike`, then this is unavoidable;
- the reasoning for the old definition was
  "it's slightly easier to prove `μ ≤ ν` this way";
  the counter-argument is
  "it's slightly harder to apply `μ ≤ ν` this way".

### Other changes

- golf some proofs broken by this change;
- add `@[gcongr]` tags to some `ENNReal` lemmas;
- fix the name
  `ENNReal.coe_lt_coe_of_le` -> `ENNReal.ENNReal.coe_lt_coe_of_lt`;
- drop an unneeded `MeasurableSet` assumption
  in `set_lintegral_pdf_le_map`
dagurtomas pushed a commit that referenced this pull request Mar 22, 2024
Redefine `≤` on `MeasureTheory.Measure`
so that `μ ≤ ν ↔ ∀ s, μ s ≤ ν s` by definition
instead of `∀ s, MeasurableSet s → μ s ≤ ν s`.

### Reasons

- this way it is defeq to `≤` on outer measures;
- if we decide to introduce an order on all `DFunLike` types
  **and** migrate measures to `FunLike`, then this is unavoidable;
- the reasoning for the old definition was
  "it's slightly easier to prove `μ ≤ ν` this way";
  the counter-argument is
  "it's slightly harder to apply `μ ≤ ν` this way".

### Other changes

- golf some proofs broken by this change;
- add `@[gcongr]` tags to some `ENNReal` lemmas;
- fix the name
  `ENNReal.coe_lt_coe_of_le` -> `ENNReal.ENNReal.coe_lt_coe_of_lt`;
- drop an unneeded `MeasurableSet` assumption
  in `set_lintegral_pdf_le_map`
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