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changes on dependent issues
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Biiiilly committed Oct 20, 2022
1 parent 9600012 commit 3e7eb7d
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4 changes: 4 additions & 0 deletions src/linear_algebra/clifford_algebra/basic.lean
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@ Authors: Eric Wieser, Utensil Song
import algebra.ring_quot
import linear_algebra.tensor_algebra.basic
import linear_algebra.quadratic_form.isometry
import tactic.equiv_rw

/-!
# Clifford Algebras
Expand Down Expand Up @@ -313,6 +314,9 @@ def invertible_ι_of_invertible (m : M) [invertible (Q m)] : invertible (ι Q m)
mul_inv_of_self := by rw [map_smul, mul_smul_comm, ι_sq_scalar, algebra.smul_def, ←map_mul,
inv_of_mul_self, map_one] }

def invertible_of_invertible_ι (m : M) [invertible (ι Q m)] [invertible (2 : R)] :
invertible (Q m) := sorry

/-- For a vector with invertible quadratic form, $v^{-1} = \frac{v}{Q(v)}$ -/
lemma inv_of_ι (m : M) [invertible (Q m)] [invertible (ι Q m)] : ⅟(ι Q m) = ι Q (⅟(Q m) • m) :=
begin
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20 changes: 4 additions & 16 deletions src/linear_algebra/clifford_algebra/spin_group.lean
Original file line number Diff line number Diff line change
Expand Up @@ -45,18 +45,6 @@ section pin
open clifford_algebra mul_action
open_locale pointwise

section other_PR
def invertible_of_invertible_ι (Q : quadratic_form R M) (m : M) [invertible (ι Q m)]
[invertible (2 : R)] : invertible (Q m) := sorry
lemma ι_mul_ι_mul_inv_of_ι (a b : M) [invertible (ι Q a)] [invertible (Q a)] :
ι Q a * ι Q b * ⅟(ι Q a) = ι Q ((⅟(Q a) * quadratic_form.polar Q a b) • a - b) := sorry
lemma inv_of_ι_mul_ι_mul_ι (a b : M) [invertible (ι Q a)] [invertible (Q a)] :
⅟(ι Q a) * ι Q b * ι Q a = ι Q ((⅟(Q a) * quadratic_form.polar Q a b) • a - b) := sorry
lemma map_inv_of {R : Type*} {S : Type*} {F : Type*} [mul_one_class R] [monoid S]
[monoid_hom_class F R S] (f : F) (r : R) [invertible r] [invertible (f r)] :
f (⅟r) = ⅟(f r) := sorry
end other_PR

/-- `lipschitz` is the subgroup closure of all the elements in the form of `ι Q m` where `ι`
is the canonical linear map `M →ₗ[R] clifford_algebra Q`. -/
def lipschitz (Q : quadratic_form R M) :=
Expand All @@ -82,7 +70,7 @@ begin
congr';
simp only [hz.symm, subsingleton.helim (congr_arg invertible hz.symm)], },
letI := invertible_of_invertible_ι Q z,
refine ⟨(⅟(Q z) * quadratic_form.polar Q z b) • z - b, (ι_mul_ι_mul_inv_of_ι z b).symm⟩, },
refine ⟨(⅟(Q z) * quadratic_form.polar Q z b) • z - b, (ι_mul_ι_mul_inv_of_ι Q z b).symm⟩, },
{ rintros x ⟨z, hz1⟩ y ⟨a, ⟨b, hb⟩, ha2⟩,
simp only [conj_act.to_conj_act_inv, distrib_mul_action.to_linear_map_apply,
has_smul.smul, conj_act.of_conj_act_inv, conj_act.of_conj_act_to_conj_act,
Expand All @@ -98,7 +86,7 @@ begin
congr';
simp only [hz1.symm, subsingleton.helim (congr_arg invertible hz1.symm)], },
letI := invertible_of_invertible_ι Q z,
refine ⟨(⅟(Q z) * quadratic_form.polar Q z b) • z - b, (inv_of_ι_mul_ι_mul_ι z b).symm⟩, },
refine ⟨(⅟(Q z) * quadratic_form.polar Q z b) • z - b, (inv_of_ι_mul_ι_mul_ι Q z b).symm⟩, },
{ simp only [conj_act.to_conj_act_one, one_smul, le_refl], },
{ intros x y hx1 hy1 z hz1,
simp only [conj_act.to_conj_act_mul] at hz1,
Expand Down Expand Up @@ -142,7 +130,7 @@ begin
{ exact subsingleton.helim (congr_arg invertible hz.symm) _ _, }, },
letI := invertible_of_invertible_ι Q z,
refine ⟨-((⅟(Q z) * quadratic_form.polar Q z y) • z - y), by simp only
[map_neg, neg_mul, ι_mul_ι_mul_inv_of_ι z y]⟩, },
[map_neg, neg_mul, ι_mul_ι_mul_inv_of_ι Q z y]⟩, },
{ rintros x ⟨z, hz⟩ y,
letI := x.invertible,
letI : invertible (ι Q z) := by rwa hz,
Expand All @@ -159,7 +147,7 @@ begin
{ exact hz.symm, }, },
letI := invertible_of_invertible_ι Q z,
refine ⟨-((⅟(Q z) * quadratic_form.polar Q z y) • z - y), by simp only
[map_neg, neg_mul, inv_of_ι_mul_ι_mul_ι z y]⟩, },
[map_neg, neg_mul, inv_of_ι_mul_ι_mul_ι Q z y]⟩, },
{ simp only [units.coe_one, map_one, one_mul, inv_one, mul_one,
linear_map.mem_range, exists_apply_eq_apply, forall_const], },
{ intros a b ha hb y,
Expand Down

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