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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_depth.ma".
16 include "delayed_updating/syntax/path_structure.ma".
17 include "delayed_updating/syntax/path_balanced.ma".
18 include "delayed_updating/syntax/prototerm_constructors.ma".
19 include "delayed_updating/substitution/fsubst.ma".
20 include "delayed_updating/notation/relations/black_rightarrow_df_4.ma".
22 (* DELAYED FOCUSED REDUCTION ************************************************)
24 inductive dfr (p) (q) (t): predicate prototerm ≝
27 r◖𝗱(↑❘q❘) ϵ t → ⊓(⊗b) → dfr p q t (t[⋔r←𝛗(↑❘q❘).t⋔(p◖𝗦)])
31 "focused balanced reduction with delayed updating (prototerm)"
32 'BlackRightArrowDF t1 p q t2 = (dfr p q t1 t2).