[Merged by Bors] - chore(GroupExtension/Basic): add lemmas about extensions by (non-abelian) groups#20998
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[Merged by Bors] - chore(GroupExtension/Basic): add lemmas about extensions by (non-abelian) groups#20998
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PR summary 5b40201a94Import changes for modified filesNo significant changes to the import graph Import changes for all files
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erdOne
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Jan 25, 2025
`GroupExtension.Equiv` now contains the inverse as data. Use `GroupExtension.Equiv.ofMonoidHom` to instantiate without providing the inverse.
Co-authored-by: Andrew Yang <36414270+erdOne@users.noreply.github.com>
erdOne
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Feb 5, 2025
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🚀 Pull request has been placed on the maintainer queue by erdOne. |
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Feb 7, 2025
…ian) groups (#20998) As the second part of #19582, this PR mostly contains the changes to the `Basic` file. It mainly: - redefines `GroupExtension.Equiv` with `MulEquiv` rather than `MonoidHom`; - adds lemmas that do not require a commutative group, as a preparation for the main PR; - defines `GroupExtension.Splitting.semidirectProductMulEquiv`, an isomorphism between the group associated to a split extension and a semidirect product; and - defines `GroupExtension.ConjClasses`, the conjugacy classes of splittings. It also contains some definitions and lemmas unused in the main PR, such as: - `GroupExtension.quotientRangeInlEquivRight`, provided as a shorthand for end-users; and - `GroupExtension.Section.section_inv_mul_mem_range`, provided as a symmetric counterpart of a required lemma. They may be dropped if this PR would introduce a too large diff. Moves: - GroupExtension.Equiv.mk -> GroupExtension.Equiv.ofMonoidHom
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As the second part of #19582, this PR mostly contains the changes to the
Basicfile.It mainly:
GroupExtension.EquivwithMulEquivrather thanMonoidHom;GroupExtension.Splitting.semidirectProductMulEquiv, an isomorphism between the group associated to a split extension and a semidirect product; andGroupExtension.ConjClasses, the conjugacy classes of splittings.It also contains some definitions and lemmas unused in the main PR, such as:
GroupExtension.quotientRangeInlEquivRight, provided as a shorthand for end-users; andGroupExtension.Section.section_inv_mul_mem_range, provided as a symmetric counterpart of a required lemma.They may be dropped if this PR would introduce a too large diff.
Moves: