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4 (* ||A|| A project by Andrea Asperti *)
6 (* ||I|| Developers: *)
7 (* ||T|| The HELM team. *)
8 (* ||A|| http://helm.cs.unibo.it *)
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15 include "delayed_updating/substitution/fsubst.ma".
16 include "delayed_updating/syntax/prototerm_constructors.ma".
17 include "delayed_updating/syntax/prototerm_eq.ma".
18 include "delayed_updating/syntax/path_head.ma".
19 include "delayed_updating/syntax/path_depth.ma".
20 include "delayed_updating/syntax/path_reverse.ma".
21 include "delayed_updating/notation/relations/black_rightarrow_df_4.ma".
23 (* DELAYED FOCUSED REDUCTION ************************************************)
25 definition dfr (p) (q): relation2 prototerm prototerm ≝
28 ∧∧ (𝗟◗q)ᴿ = ↳[n](rᴿ) & r◖𝗱n ϵ t1 &
29 t1[⋔r←𝛕n.(t1⋔(p◖𝗦))] ⇔ t2
33 "focused reduction with delayed updating (prototerm)"
34 'BlackRightArrowDF t1 p q t2 = (dfr p q t1 t2).