v ∈ vols ⊦ (∅)[v0] = to-vtbl(vols)[v0], v0 ∈ vols
Used simplifier rules: to-vtbl-in: ⊦ v ∈ to-vtbl(vols) ↔ v ∈ vols;% ⊦ v ∈ vols -- v0 ↔ v ≠ v0 ∧ v ∈ vols; (s)