| ⊦ ri[key0, adr] |≤ key1 = (ri |≤ key1)[key0, adr], key1 < key0 |
⊦ ri = ri0 ↔ (∀ key. (key ∈ ri ↔ key ∈ ri0) ∧ (key ∈ ri → ri[key] = ri0[key]))
⊦ key1 < key0, ∀ key. (key ∈ ri[key0, adr] |≤ key1 ↔ key ∈ (ri |≤ key1)[key0, adr]) ∧ (key ∈ ri[key0, adr] |≤ key1 → (ri[key0, adr] |≤ key1)[key] = (ri |≤ key1)[key0, adr][key])
Used terms: (ri |≤ key1)[key0, adr], ri[key0, adr] |≤ key1