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@jsm28 jsm28 commented Oct 12, 2025

Add a lemma that orthogonalProjection s₁ (orthogonalProjection s₂ p) = orthogonalProjection s₁ p for s₁ ≤ s₂. (A similar lemma for projection onto submodules rather than affine subspaces already exists.)


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…Projection_of_le`

Add a lemma that `orthogonalProjection s₁ (orthogonalProjection s₂ p)
= orthogonalProjection s₁ p` for `s₁ ≤ s₂`. (A similar lemma for
projection onto submodules rather than affine subspaces already
exists.)
@jsm28 jsm28 added the t-euclidean-geometry Affine and axiomatic geometry label Oct 12, 2025
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github-actions bot commented Oct 12, 2025

PR summary 8aa3ccd118

Import changes for modified files

No significant changes to the import graph

Import changes for all files
Files Import difference

Declarations diff

+ coe_orthogonalProjection_eq_iff_mem
+ orthogonalProjection_eq_iff_mem
+ orthogonalProjection_eq_orthogonalProjection_iff_vsub_mem
+ orthogonalProjection_orthogonalProjection_of_le

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).

jsm28 added 3 commits October 19, 2025 21:39
Add a lemma

```lean
lemma orthogonalProjection_eq_iff_mem {s : AffineSubspace ℝ P} [Nonempty s]
    [s.direction.HasOrthogonalProjection] {p q : P} :
    orthogonalProjection s p = q ↔ q ∈ s ∧ p -ᵥ q ∈ s.directionᗮ := by
```

that gives the characteristic property of the orthogonal projection in
a more convenient form to use than the existing
`inter_eq_singleton_orthogonalProjection` (from which it is derived).
@mathlib4-dependent-issues-bot mathlib4-dependent-issues-bot added the blocked-by-other-PR This PR depends on another PR (this label is automatically managed by a bot) label Oct 19, 2025
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