fddc8b06ac
Fix issue reported at https://leanprover.zulipchat.com/#narrow/stream/270676-lean4/topic/'rewrite'.20failed.20but.20it.20should.20work/near/274870747
12 lines
441 B
Text
12 lines
441 B
Text
class Foo (α : Type) where
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decEq : DecidableEq α
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instance instDecidableEq {α} [Foo α] : DecidableEq α := Foo.decEq
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instance instFooNat : Foo Nat := ⟨by infer_instance⟩
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def kron (i j : α) [DecidableEq α] : Nat := if (i=j) then 1 else 0
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theorem kron_right_mul (α : Type) [foo : Foo α] (i j : α) (x : Nat) : x * kron i j = kron i j * x := sorry
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example {i j : Nat} : i * kron i j = kron i j * i := by
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rw [kron_right_mul]
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