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feat(Analysis/BoxIntegral/UnitPartition): Prove results linking integral point counting and integrals #12405

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@xroblot xroblot commented Apr 24, 2024

We prove the following result:

Let s be a bounded, measurable set of ι → ℝ whose frontier has zero volume and let F be a
continuous function. Then the limit as n → ∞ of ∑ F x / n ^ card ι, where the sum is over the
points in s ∩ n⁻¹ • (ι → ℤ), tends to the integral of F over s.

using Riemann integration. As a special case, we deduce that

The limit as n → ∞ of card (s ∩ n⁻¹ • (ι → ℤ)) / n ^ card ι tends to the volume of s.

Both of these statements are for a variable n : ℕ. However, with the additional hypothesis:
x • s ⊆ y • s whenever 0 < x ≤ y, we generalize the previous statement to a real variable.

This PR is part of the proof of the Analytic Class Number Formula.


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@xroblot xroblot added WIP Work in progress t-analysis Analysis (normed *, calculus) labels Apr 24, 2024
@leanprover-community-mathlib4-bot leanprover-community-mathlib4-bot added the merge-conflict The PR has a merge conflict with master, and needs manual merging. (this label is managed by a bot) label Jul 12, 2024
@xroblot xroblot changed the title feat(Analysis/BoxIntegral): Add UnitPartition feat(Analysis/BoxIntegral/UnitPartition): Prove results linking lattice point counting and integrals Sep 10, 2024
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github-actions bot commented Sep 12, 2024

PR summary 06b4225384

Import changes exceeding 2%

% File
+4.49% Mathlib.Analysis.BoxIntegral.UnitPartition

Import changes for modified files

Dependency changes

File Base Count Head Count Change
Mathlib.Analysis.BoxIntegral.UnitPartition 1892 1977 +85 (+4.49%)
Import changes for all files
Files Import difference
Mathlib.Analysis.BoxIntegral.UnitPartition 85

Declarations diff

+ ContinuousOn.continuousAt_mulIndicator
+ _root_.tendsto_card_div_pow_atTop_volume
+ _root_.tendsto_card_div_pow_atTop_volume'
+ _root_.tendsto_tsum_div_pow_atTop_integral
+ eqOn_mulIndicator'
+ eq_of_mem_smul_span_of_index_eq_index
+ integralSum_eq_tsum_div
+ mem_smul_span_iff
+ repr_isUnitSMul
+ setFinite_inter
+ smul
+ tag_index_eq_self_of_mem_smul_span
+ tag_mem_smul_span

You can run this locally as follows
## summary with just the declaration names:
./scripts/declarations_diff.sh <optional_commit>

## more verbose report:
./scripts/declarations_diff.sh long <optional_commit>

The doc-module for script/declarations_diff.sh contains some details about this script.


No changes to technical debt.

You can run this locally as

./scripts/technical-debt-metrics.sh pr_summary
  • The relative value is the weighted sum of the differences with weight given by the inverse of the current value of the statistic.
  • The absolute value is the relative value divided by the total sum of the inverses of the current values (i.e. the weighted average of the differences).

@leanprover-community-bot-assistant leanprover-community-bot-assistant removed the merge-conflict The PR has a merge conflict with master, and needs manual merging. (this label is managed by a bot) label Sep 12, 2024
@mathlib4-dependent-issues-bot mathlib4-dependent-issues-bot added the blocked-by-other-PR This PR depends on another PR to Mathlib (this label is automatically managed by a bot) label Sep 13, 2024
@xroblot xroblot removed the WIP Work in progress label Sep 13, 2024
@xroblot xroblot changed the title feat(Analysis/BoxIntegral/UnitPartition): Prove results linking lattice point counting and integrals feat(Analysis/BoxIntegral/UnitPartition): Prove results linking integral point counting and integrals Sep 15, 2024
@xroblot xroblot added the WIP Work in progress label Nov 30, 2024
@xroblot xroblot removed the WIP Work in progress label Dec 1, 2024
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xroblot commented Dec 1, 2024

@MichaelStollBayreuth, I think I have addressed all of your comments. Thanks a lot for your extensive review!

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This looks good to me now.

maintainer merge

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github-actions bot commented Dec 1, 2024

🚀 Pull request has been placed on the maintainer queue by MichaelStollBayreuth.

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bors d+

· rw [setIntegral_const, smul_eq_mul, mul_one]

private def tendsto_card_div_pow₁ {c : ℝ} (hc : c ≠ 0) :
↑(s ∩ c⁻¹ • L) ≃ ↑(c • s ∩ L) :=
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Suggested change
↑(s ∩ c⁻¹ • L) ≃ ↑(c • s ∩ L) :=
↑(s ∩ c⁻¹ • L) ≃ ↑(c • s ∩ L) :=

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mathlib-bors bot commented Dec 2, 2024

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

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xroblot commented Dec 2, 2024

bors r+

mathlib-bors bot pushed a commit that referenced this pull request Dec 2, 2024
…ral point counting and integrals (#12405)

We prove the following result:

> Let `s` be a bounded, measurable set of `ι → ℝ` whose frontier has zero volume and let `F` be a 
> continuous function. Then the limit as `n → ∞` of `∑ F x / n ^ card ι`, where the sum is over the
> points in `s ∩ n⁻¹ • (ι → ℤ)`, tends to the integral of `F` over `s`.

using Riemann integration. As a special case, we deduce that 

> The limit as `n → ∞` of `card (s ∩ n⁻¹ • (ι → ℤ)) / n ^ card ι` tends to the volume of `s`.

Both of these statements are for a variable `n : ℕ`. However, with the additional hypothesis: 
`x • s ⊆ y • s` whenever `0 < x ≤ y`, we generalize the previous statement to a real variable. 

This PR is part of the proof of the Analytic Class Number Formula.



Co-authored-by: Xavier Roblot <[email protected]>
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