lean2/tests/lean/tactic14.lean

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(**
-- Tactic for trying to prove goal using Reflexivity, Congruence and available assumptions
congr_tac = TRY(unfold_tac("eq")) ..REPEAT(ORELSE(apply_tac("Refl"), apply_tac("Congr"), assumption_tac))
**)
Theorem T1 (a b : Int) (f : Int -> Int) : a = b -> (f (f a)) = (f (f b)) :=
fun assumption : a = b,
show (f (f a)) = (f (f b)) by congr_tac
Show Environment 1.