-definition fle: bi_relation lenv term ≝ λL1,T1,L2,T2.
- ∃∃n1,n2,f1,f2. L1 ⊢ 𝐅*⦃T1⦄ ≡ f1 & L2 ⊢ 𝐅*⦃T2⦄ ≡ f2 &
- L1 ≋ⓧ*[n1, n2] L2 & ⫱*[n1]f1 ⊆ ⫱*[n2]f2.
-
-interpretation "free variables inclusion (restricted closure)"
- 'SubSetEq L1 T1 L2 T2 = (fle L1 T1 L2 T2).
-
-(* Basic properties *********************************************************)
-
-lemma fle_sort: ∀L,s1,s2. ⦃L, ⋆s1⦄ ⊆ ⦃L, ⋆s2⦄.
-/3 width=8 by frees_sort, sle_refl, ex4_4_intro/ qed.
-
-lemma fle_gref: ∀L,l1,l2. ⦃L, §l1⦄ ⊆ ⦃L, §l2⦄.
-/3 width=8 by frees_gref, sle_refl, ex4_4_intro/ qed.