Skip to content

[Merged by Bors] - feat(LinearAlgebra/Matrix/SpecialLinearGroup): Add action on R^n #39581

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
Whysoserioushah wants to merge 3 commits into from
Closed

[Merged by Bors] - feat(LinearAlgebra/Matrix/SpecialLinearGroup): Add action on R^n #39581

Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
7ab90e1
add action
Whysoserioushah May 19, 2026
88504b1
add matrix namespace
Whysoserioushah May 19, 2026
5e6db46
mark lemma protected and change name
Whysoserioushah May 22, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
25 changes: 25 additions & 0 deletions Mathlib/LinearAlgebra/Matrix/SpecialLinearGroup.lean
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ Authors: Anne Baanen, Wen Yang
module

public import Mathlib.Data.Fintype.Parity
public import Mathlib.Data.Matrix.Action
public import Mathlib.LinearAlgebra.Matrix.Adjugate
public import Mathlib.LinearAlgebra.Matrix.ToLin
public import Mathlib.LinearAlgebra.Matrix.Transvection
Expand Down Expand Up @@ -461,6 +462,30 @@ lemma mulVecSL {v : Fin 2 → R} (hab : IsCoprime (v 0) (v 1)) (A : SL(2, R)) :

end IsCoprime

namespace Matrix

section Action
Comment thread
Whysoserioushah marked this conversation as resolved.

variable {F : Type*} [CommRing F] {ι : Type*} [DecidableEq ι] [Fintype ι]

instance : DistribMulAction (Matrix.SpecialLinearGroup ι F) (ι → F) where
smul m v := m.1 • v
smul_zero _ := smul_zero (M := Matrix ι ι F) _
Comment thread
Whysoserioushah marked this conversation as resolved.
smul_add _ := smul_add (M := Matrix ι ι F) _
one_smul _ := one_smul (M := Matrix ι ι F) _
mul_smul _ _ _ := SemigroupAction.mul_smul (α := Matrix ι ι F) _ _ _

instance : SMulCommClass (Matrix.SpecialLinearGroup ι F) F (ι → F) where
smul_comm m k v := show m.1 • k • v = k • m.1 • v from smul_comm _ _ _

protected lemma SpecialLinearGroup.smul_def
(m : Matrix.SpecialLinearGroup ι F) (v : ι → F) :
m • v = m.1 • v := rfl

end Action

end Matrix

namespace ModularGroup

open MatrixGroups
Expand Down
Loading