| ri[key0] = ri[key1], key0 ∈ ri, key1 ∈ ri, ∀ key0, key1. key0 ∈ ri ∧ key1 ∈ ri ∧ ri[key0] = ri[key1] → key0 = key1 ⊦ key0 = key1, key0 = key, key1 = key |
ri[key0] = ri[key1], key1 ∈ ri, key0 ∈ ri, key1 ∈ ri ∧ key1 ∈ ri ∧ ri[key1] = ri[key1] → key1 = key1, ∀ key0, key1. key0 ∈ ri ∧ key1 ∈ ri ∧ ri[key0] = ri[key1] → key0 = key1 ⊦ key0 = key, key0 = key1, key1 = key
Used terms: key1, key1