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[Merged by Bors] - feat(analysis/convex/caratheodory): strengthen Caratheodory's lemma to provide affine independence #8892
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Evidently, these are just thin wrappers around `well_founded.min` but I think this use case is common enough to deserve this specialisation.
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…o provide affine independence
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🎉 Great news! Looks like all the dependencies have been resolved: 💡 To add or remove a dependency please update this issue/PR description. Brought to you by Dependent Issues (:robot: ). Happy coding! |
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Thanks a lot for this!
Incidentally, I need this strenghtened Carathéodory for my next PR (convex independence). 😁
I particularly like the new explanation in the module docstring.
Co-authored-by: Yaël Dillies <yael.dillies@gmail.com>
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Thanks 🎉
bors merge
…o provide affine independence (#8892) The changes here are: - Use hypothesis `¬ affine_independent ℝ (coe : t → E)` instead of `finrank ℝ E + 1 < t.card` - Drop no-longer-necessary `[finite_dimensional ℝ E]` assumption - Do not use a shrinking argument but start by choosing an appropriate subset of minimum cardinality via `min_card_finset_of_mem_convex_hull` - Provide a single alternative form of Carathéodory's lemma `eq_pos_convex_span_of_mem_convex_hull` - In the alternate form, define the explicit linear combination using elements parameterised by a new `fintype` rather than on the entire ambient space `E` (we thus avoid the issue of junk values outside of the relevant subset)
Build failed (retrying...): |
…o provide affine independence (#8892) The changes here are: - Use hypothesis `¬ affine_independent ℝ (coe : t → E)` instead of `finrank ℝ E + 1 < t.card` - Drop no-longer-necessary `[finite_dimensional ℝ E]` assumption - Do not use a shrinking argument but start by choosing an appropriate subset of minimum cardinality via `min_card_finset_of_mem_convex_hull` - Provide a single alternative form of Carathéodory's lemma `eq_pos_convex_span_of_mem_convex_hull` - In the alternate form, define the explicit linear combination using elements parameterised by a new `fintype` rather than on the entire ambient space `E` (we thus avoid the issue of junk values outside of the relevant subset)
Build failed (retrying...): |
…o provide affine independence (#8892) The changes here are: - Use hypothesis `¬ affine_independent ℝ (coe : t → E)` instead of `finrank ℝ E + 1 < t.card` - Drop no-longer-necessary `[finite_dimensional ℝ E]` assumption - Do not use a shrinking argument but start by choosing an appropriate subset of minimum cardinality via `min_card_finset_of_mem_convex_hull` - Provide a single alternative form of Carathéodory's lemma `eq_pos_convex_span_of_mem_convex_hull` - In the alternate form, define the explicit linear combination using elements parameterised by a new `fintype` rather than on the entire ambient space `E` (we thus avoid the issue of junk values outside of the relevant subset)
Build failed (retrying...): |
…o provide affine independence (#8892) The changes here are: - Use hypothesis `¬ affine_independent ℝ (coe : t → E)` instead of `finrank ℝ E + 1 < t.card` - Drop no-longer-necessary `[finite_dimensional ℝ E]` assumption - Do not use a shrinking argument but start by choosing an appropriate subset of minimum cardinality via `min_card_finset_of_mem_convex_hull` - Provide a single alternative form of Carathéodory's lemma `eq_pos_convex_span_of_mem_convex_hull` - In the alternate form, define the explicit linear combination using elements parameterised by a new `fintype` rather than on the entire ambient space `E` (we thus avoid the issue of junk values outside of the relevant subset)
Pull request successfully merged into master. Build succeeded: |
The changes here are:
¬ affine_independent ℝ (coe : t → E)
instead offinrank ℝ E + 1 < t.card
[finite_dimensional ℝ E]
assumptionmin_card_finset_of_mem_convex_hull
eq_pos_convex_span_of_mem_convex_hull
fintype
rather than on the entire ambient spaceE
(we thus avoid the issue of junk values outside of the relevant subset)function.argmin
,function.argmin_on
#8895