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[Merged by Bors] - chore(ExteriorAlgebra.Grading): drop ExteriorAlgebra.instZero #9274

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[Merged by Bors] - chore(ExteriorAlgebra.Grading): drop ExteriorAlgebra.instZero #9274

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3 changes: 1 addition & 2 deletions Mathlib/LinearAlgebra/ExteriorAlgebra/Grading.lean
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Expand Up @@ -44,8 +44,7 @@ theorem GradedAlgebra.ι_apply (m : M) :

-- Porting note: Lean needs to be reminded of this instance otherwise it cannot
-- synthesize 0 in the next theorem
instance (α : Type*) [MulZeroClass α] : Zero α := MulZeroClass.toZero

attribute [instance 1100] MulZeroClass.toZero in
theorem GradedAlgebra.ι_sq_zero (m : M) : GradedAlgebra.ι R M m * GradedAlgebra.ι R M m = 0 := by
rw [GradedAlgebra.ι_apply, DirectSum.of_mul_of]
refine DFinsupp.single_eq_zero.mpr (Subtype.ext <| ExteriorAlgebra.ι_sq_zero _)
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