| ⊦ ri-closed(ri, fs, ro) → ( ri-closed(ri0, fs0, ro0) ↔ (∀ key. (key ∈ ri → ri[key] ∈ fs ∧ node-closed(fs[ri[key]], ri, fs, ro)) → key ∈ ri0 → ri0[key] ∈ fs0 ∧ node-closed(fs0[ri0[key]], ri0, fs0, ro0))) |
ri-closed(ri, fs, ro) ⊦ ri-closed(ri0, fs0, ro0) ↔ (∀ key. (key ∈ ri → ri[key] ∈ fs ∧ node-closed(fs[ri[key]], ri, fs, ro)) → key ∈ ri0 → ri0[key] ∈ fs0 ∧ node-closed(fs0[ri0[key]], ri0, fs0, ro0))