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4 (* ||A|| A project by Andrea Asperti *)
6 (* ||I|| Developers: *)
7 (* ||T|| The HELM team. *)
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15 include "delayed_updating/syntax/path_structure.ma".
16 include "delayed_updating/syntax/path_balanced.ma".
17 include "delayed_updating/substitution/fsubst.ma".
18 include "delayed_updating/substitution/lift_preterm.ma".
19 include "delayed_updating/notation/relations/black_rightarrow_f_4.ma".
21 (* IMMEDIATE FOCUSED REDUCTION ************************************************)
23 inductive ifr (p) (q) (t): predicate preterm ≝
26 r◖𝗱❨n❩ ϵ t → ⊓⊗b → ifr p q t (t[⋔r←↑[𝐮❨n❩]t⋔(p◖𝗦)])
30 "focused balanced reduction with immediate updating (preterm)"
31 'BlackRightArrowF t1 p q t2 = (ifr p q t1 t2).