lean4-htt/tests/lean/449.lean
Leonardo de Moura 2a676b6dfb fix: fixes #449
2021-05-10 13:10:59 -07:00

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open Nat
theorem mul_comm (m n : Nat) : m * n = n * m := by
induction n with
| zero => simp
| succ n ih =>
have foo : m * n + m = m * n + (succ zero) * m := _
rfl
theorem test (o : x y) : x := by
cases o with
| inl h => exact h
| inr h => exact _