| ⊦ (ri ⊖ ro) \ datakeys(key, n, ri) = (ri \ datakeys(key, n, ri)) ⊖ ro, key ∈ ro |
⊦ ri = ri0 ↔ (∀ key. (key ∈ ri ↔ key ∈ ri0) ∧ (key ∈ ri → ri[key] = ri0[key]))
⊦ key ∈ ro, ∀ key0. (key0 ∈ (ri ⊖ ro) \ datakeys(key, n, ri) ↔ key0 ∈ (ri \ datakeys(key, n, ri)) ⊖ ro) ∧ (key0 ∈ (ri ⊖ ro) \ datakeys(key, n, ri) → ((ri ⊖ ro) \ datakeys(key, n, ri))[key0] = ((ri \ datakeys(key, n, ri)) ⊖ ro)[key0])
Used terms: (ri \ datakeys(key, n, ri)) ⊖ ro, (ri ⊖ ro) \ datakeys(key, n, ri)