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[Merged by Bors] - feat: Prove that the measure equivalence between EuclideanSpace ℝ ι and ι → ℝ is volume preserving #7037
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I'll try to find some time to review the dependency one more time in the next few days. Thanks for getting this over the finish line!
We prove some lemmas that will be useful in following PRs #6832 and #7037, mainly: ```lean theorem Basis.addHaar_eq {b : Basis ι ℝ E} {b' : Basis ι' ℝ E} : b.addHaar = b'.addHaar ↔ b.addHaar b'.parallelepiped = 1 theorem Basis.parallelepiped_eq_map (b : Basis ι ℝ E) : b.parallelepiped = (TopologicalSpace.PositiveCompacts.piIcc01 ι).map b.equivFun.symm b.equivFunL.symm.continuous theorem Basis.addHaar_map (b : Basis ι ℝ E) (f : E ≃L[ℝ] F) : map f b.addHaar = (b.map f.toLinearEquiv).addHaar ``` Co-authored-by: Eric Wieser <[email protected]>
We prove some lemmas that will be useful in following PRs #6832 and #7037, mainly: ```lean theorem Basis.addHaar_eq {b : Basis ι ℝ E} {b' : Basis ι' ℝ E} : b.addHaar = b'.addHaar ↔ b.addHaar b'.parallelepiped = 1 theorem Basis.parallelepiped_eq_map (b : Basis ι ℝ E) : b.parallelepiped = (TopologicalSpace.PositiveCompacts.piIcc01 ι).map b.equivFun.symm b.equivFunL.symm.continuous theorem Basis.addHaar_map (b : Basis ι ℝ E) (f : E ≃L[ℝ] F) : map f b.addHaar = (b.map f.toLinearEquiv).addHaar ``` Co-authored-by: Eric Wieser <[email protected]>
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bors d+
Thanks! I added a few shortcut lemmas; let me know if you agree with them.
✌️ xroblot can now approve this pull request. To approve and merge a pull request, simply reply with |
LGTM. Thanks! bors r+ |
…nd ι → ℝ is volume preserving (#7037) We prove that the two `MeasureSpace` structures on $\mathbb{R}^\iota$, the one coming from its identification with `ι→ ℝ` and the one coming from `EuclideanSpace ℝ ι`, agree in the sense that the measure equivalence between the two corresponding volumes is measure preserving. Co-authored-by: Eric Wieser <[email protected]> Co-authored-by: Eric Wieser <[email protected]>
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We prove some lemmas that will be useful in following PRs #6832 and #7037, mainly: ```lean theorem Basis.addHaar_eq {b : Basis ι ℝ E} {b' : Basis ι' ℝ E} : b.addHaar = b'.addHaar ↔ b.addHaar b'.parallelepiped = 1 theorem Basis.parallelepiped_eq_map (b : Basis ι ℝ E) : b.parallelepiped = (TopologicalSpace.PositiveCompacts.piIcc01 ι).map b.equivFun.symm b.equivFunL.symm.continuous theorem Basis.addHaar_map (b : Basis ι ℝ E) (f : E ≃L[ℝ] F) : map f b.addHaar = (b.map f.toLinearEquiv).addHaar ``` Co-authored-by: Eric Wieser <[email protected]>
…nd ι → ℝ is volume preserving (#7037) We prove that the two `MeasureSpace` structures on $\mathbb{R}^\iota$, the one coming from its identification with `ι→ ℝ` and the one coming from `EuclideanSpace ℝ ι`, agree in the sense that the measure equivalence between the two corresponding volumes is measure preserving. Co-authored-by: Eric Wieser <[email protected]> Co-authored-by: Eric Wieser <[email protected]>
We prove that the two$\mathbb{R}^\iota$ , the one coming from its identification with
MeasureSpace
structures onι→ ℝ
and the one coming fromEuclideanSpace ℝ ι
, agree in the sense that the measure equivalence between the two corresponding volumes is measure preserving.Co-authored-by: Eric Wieser [email protected]