- ∀n1,T1. ❪G0,L0❫ ⊢ T0 ➡*[n1,h] T1 → ❪G0,L0❫ ⊢ T0 ![h,a] → T0 ≛ T1 →
- ∀n2,T2. ❪G0,L0❫ ⊢ T0 ➡*[n2,h] T2 → T0 ≛ T2 →
- ∀L1. ❪G0,L0❫ ⊢ ➡[h] L1 → ∀L2. ❪G0,L0❫ ⊢ ➡[h] L2 →
- ∃∃T. ❪G0,L1❫ ⊢ T1 ➡*[n2-n1,h] T & T1 ≛ T & ❪G0,L2❫ ⊢ T2 ➡*[n1-n2,h] T & T2 ≛ T.
+ ∀n1,T1. ❪G0,L0❫ ⊢ T0 ➡*[h,n1] T1 → ❪G0,L0❫ ⊢ T0 ![h,a] → T0 ≛ T1 →
+ ∀n2,T2. ❪G0,L0❫ ⊢ T0 ➡*[h,n2] T2 → T0 ≛ T2 →
+ ∀L1. ❪G0,L0❫ ⊢ ➡[h,0] L1 → ∀L2. ❪G0,L0❫ ⊢ ➡[h,0] L2 →
+ ∃∃T. ❪G0,L1❫ ⊢ T1 ➡*[h,n2-n1] T & T1 ≛ T & ❪G0,L2❫ ⊢ T2 ➡*[h,n1-n2] T & T2 ≛ T.