-lemma cix_ib2: ∀h,g,a,I,L,V,T. ib2 a I → ⦃h, L⦄ ⊢ 𝐈[g]⦃V⦄ → ⦃h, L.ⓑ{I}V⦄ ⊢ 𝐈[g]⦃T⦄ →
- ⦃h, L⦄ ⊢ 𝐈[g]⦃ⓑ{a,I}V.T⦄.
-#h #g #a #I #L #V #T #HI #HV #HT #H
-elim (crx_inv_ib2 … HI H) -HI -H /2 width=1/
+lemma cix_ib2: ∀h,g,a,I,G,L,V,T. ib2 a I → ⦃G, L⦄ ⊢ ➡[h, g] 𝐈⦃V⦄ → ⦃G, L.ⓑ{I}V⦄ ⊢ ➡[h, g] 𝐈⦃T⦄ →
+ ⦃G, L⦄ ⊢ ➡[h, g] 𝐈⦃ⓑ{a,I}V.T⦄.
+#h #g #a #I #G #L #V #T #HI #HV #HT #H
+elim (crx_inv_ib2 … HI H) -HI -H /2 width=1 by/