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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/unwind/unwind2_prototerm.ma".
16 include "delayed_updating/substitution/fsubst.ma".
17 include "delayed_updating/syntax/prototerm_eq.ma".
18 include "delayed_updating/syntax/path_head.ma".
19 include "delayed_updating/syntax/path_reverse.ma".
20 include "delayed_updating/notation/relations/black_rightarrow_if_4.ma".
22 (* IMMEDIATE FOCUSED REDUCTION ************************************************)
24 definition ifr (p) (q): relation2 prototerm prototerm ≝
27 ∧∧ (𝗟◗q)ᴿ = ↳[n](rᴿ) & r◖𝗱n ϵ t1 &
28 t1[⋔r←▼[𝐮❨n❩](t1⋔(p◖𝗦))] ⇔ t2
32 "focused reduction with immediate updating (prototerm)"
33 'BlackRightArrowIF t1 p q t2 = (ifr p q t1 t2).