4 lines
182 B
Text
4 lines
182 B
Text
open Nat
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theorem add_assoc (m n k : Nat) : m + n + k = m + (n + k) :=
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Nat.recOn (motive := fun k => m + n + k = m + (n + k)) k rfl (fun k ih => by simp [Nat.add_assoc, ih]; done)
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