| unfold_sort: ∀G,L,k. unfold G L (⋆k) L
| unfold_lref: ∀I,G,L1,L2,K1,K2,V,i. ⬇[i] L1 ≡ K1. ⓑ{I}V →
unfold G K1 V K2 → ⬇[Ⓣ, |L2|, i] L2 ≡ K2 →
- unfold G L1 (#i) (L1;;L2)
+ unfold G L1 (#i) (L1●L2)
| unfold_bind: ∀a,I,G,L1,L2,V,T.
unfold G (L1.ⓑ{I}V) T L2 → unfold G L1 (ⓑ{a,I}V.T) L2
| unfold_flat: ∀I,G,L1,L2,V,T.