(* Basic_2A1: uses: lleq_lpx_trans *)
lemma reqx_lpx_trans (G):
∀L2,K2. ❪G,L2❫ ⊢ ⬈ K2 → ∀L1. ∀T:term. L1 ≛[T] L2 →
∃∃K1. ❪G,L1❫ ⊢ ⬈ K1 & K1 ≛[T] K2.
#G #L2 #K2 #HLK2 #L1 #T #HL12
lapply (lpx_rpx … T HLK2) -HLK2 #HLK2
(* Basic_2A1: uses: lleq_lpx_trans *)
lemma reqx_lpx_trans (G):
∀L2,K2. ❪G,L2❫ ⊢ ⬈ K2 → ∀L1. ∀T:term. L1 ≛[T] L2 →
∃∃K1. ❪G,L1❫ ⊢ ⬈ K1 & K1 ≛[T] K2.
#G #L2 #K2 #HLK2 #L1 #T #HL12
lapply (lpx_rpx … T HLK2) -HLK2 #HLK2