/5 width=5 by fpbc_fpbg, fpbu_fpbc, lstas_fpbu/ qed.
lemma sta_fpbg: ∀h,g,G,L,T1,T2,l. ⦃G, L⦄ ⊢ T1 ▪[h, g] l+1 →
- ⦃G, L⦄ ⊢ T1 •[h] T2 → ⦃G, L, T1⦄ >≡[h, g] ⦃G, L, T2⦄.
+ ⦃G, L⦄ ⊢ T1 •*[h, 1] T2 → ⦃G, L, T1⦄ >≡[h, g] ⦃G, L, T2⦄.
/4 width=2 by fpbc_fpbg, fpbu_fpbc, sta_fpbu/ qed.