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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 "basic_2/notation/relations/lazyeq_8.ma".
16 include "basic_2/computation/lpxs.ma".
18 (* EQUIVALENT "BIG TREE" NORMAL FORMS ***************************************)
20 (* Note: this definition works but is not symmetric nor decidable *)
21 definition fleq: ∀h. sd h → tri_relation genv lenv term ≝
22 λh,g,G1,L1,T1,G2,L2,T2.
23 ∧∧ G1 = G2 & ⦃G1, L1⦄ ⊢ ➡*[h, g] L2 & T1 = T2.
26 "equivalent 'big tree' normal forms (closure)"
27 'LazyEq h g G1 L1 T1 G2 L2 T2 = (fleq h g G1 L1 T1 G2 L2 T2).
29 (* Basic_properties *********************************************************)
31 lemma fleq_refl: ∀h,g. tri_reflexive … (fleq h g).
32 /2 width=1 by and3_intro/ qed.