-lemma lpx_inv_pair: ∀h,I1,I2,G,L1,L2,V1,V2. ⦃G, L1.ⓑ{I1}V1⦄ ⊢ ⬈[h] L2.ⓑ{I2}V2 →
- ∧∧ ⦃G, L1⦄ ⊢ ⬈[h] L2 & ⦃G, L1⦄ ⊢ V1 ⬈[h] V2 & I1 = I2.
+lemma lpx_inv_unit_sn (h) (G): ∀I,L2,K1. ⦃G,K1.ⓤ{I}⦄ ⊢ ⬈[h] L2 →
+ ∃∃K2. ⦃G,K1⦄ ⊢ ⬈[h] K2 & L2 = K2.ⓤ{I}.
+/2 width=1 by lex_inv_unit_sn/ qed-.
+
+(* Basic_2A1: was: lpx_inv_pair1 *)
+lemma lpx_inv_pair_sn (h) (G): ∀I,L2,K1,V1. ⦃G,K1.ⓑ{I}V1⦄ ⊢ ⬈[h] L2 →
+ ∃∃K2,V2. ⦃G,K1⦄ ⊢ ⬈[h] K2 & ⦃G,K1⦄ ⊢ V1 ⬈[h] V2 &
+ L2 = K2.ⓑ{I}V2.
+/2 width=1 by lex_inv_pair_sn/ qed-.
+
+lemma lpx_inv_unit_dx (h) (G): ∀I,L1,K2. ⦃G,L1⦄ ⊢ ⬈[h] K2.ⓤ{I} →
+ ∃∃K1. ⦃G,K1⦄ ⊢ ⬈[h] K2 & L1 = K1.ⓤ{I}.
+/2 width=1 by lex_inv_unit_dx/ qed-.
+
+(* Basic_2A1: was: lpx_inv_pair2 *)
+lemma lpx_inv_pair_dx (h) (G): ∀I,L1,K2,V2. ⦃G,L1⦄ ⊢ ⬈[h] K2.ⓑ{I}V2 →
+ ∃∃K1,V1. ⦃G,K1⦄ ⊢ ⬈[h] K2 & ⦃G,K1⦄ ⊢ V1 ⬈[h] V2 &
+ L1 = K1.ⓑ{I}V1.
+/2 width=1 by lex_inv_pair_dx/ qed-.
+
+lemma lpx_inv_pair (h) (G): ∀I1,I2,L1,L2,V1,V2. ⦃G,L1.ⓑ{I1}V1⦄ ⊢ ⬈[h] L2.ⓑ{I2}V2 →
+ ∧∧ ⦃G,L1⦄ ⊢ ⬈[h] L2 & ⦃G,L1⦄ ⊢ V1 ⬈[h] V2 & I1 = I2.