+ (ReductionTactics.change_tac
+ ~pattern:(ProofEngineTypes.conclusion_pattern
+ (Some new_t1'))
+ (fun _ m u ->
+ C.Appl [ C.Lambda (C.Name "x", tty,
+ C.MutCase (turi, typeno,
+ (C.Lambda ((C.Name "x"),
+ (S.lift 1 tty),
+ (S.lift 2 tty'))),
+ (C.Rel 1), pattern
+ )
+ );
+ t1], m, u))