-definition tc_dedropable_sn: predicate (relation3 lenv term term) ≝
- λR. ∀b,f,L1,K1. ⬇*[b, f] L1 ≡ K1 →
- ∀K2,T. K1 ⦻**[R, T] K2 → ∀U. ⬆*[f] T ≡ U →
- ∃∃L2. L1 ⦻**[R, U] L2 & ⬇*[b, f] L2 ≡ K2 & L1 ≡[f] L2.
+definition tc_f_dedropable_sn: predicate (relation3 lenv term term) ≝
+ λR. ∀b,f,L1,K1. ⬇*[b, f] L1 ≘ K1 →
+ ∀K2,T. K1 ⪤**[R, T] K2 → ∀U. ⬆*[f] T ≘ U →
+ ∃∃L2. L1 ⪤**[R, U] L2 & ⬇*[b, f] L2 ≘ K2 & L1 ≡[f] L2.