]
qed.
(* Basic_1: was: wcpr0_ldrop_back *)
lemma ltpr_ldrop_trans: ∀L1,K1,d,e. ↓[d, e] L1 ≡ K1 → ∀K2. K1 ⇒ K2 →
∃∃L2. ↓[d, e] L2 ≡ K2 & L1 ⇒ L2.
]
qed.
(* Basic_1: was: wcpr0_ldrop_back *)
lemma ltpr_ldrop_trans: ∀L1,K1,d,e. ↓[d, e] L1 ≡ K1 → ∀K2. K1 ⇒ K2 →
∃∃L2. ↓[d, e] L2 ≡ K2 & L1 ⇒ L2.