| 1 + # ax0 = # ay, unique_al(ay), unique_al(ax0), b ∈ ay, a ∈ ay, ∀ ay0, b0. # ax0 = # ay0 ∧ unique_al(ay0) ∧ b0 ∈ ay0 ∧ (∀ a. a ∈ ax0 → a ∈ ay0) → b0 ∈ ax0, ∀ a0. a0 ∈ ax0 → a0 ∈ ay ⊦ b = a, b ∈ ax0, a ∈ ax0 |
⊦ a ∈ ax ↔ (∃ d, ay, az. ax = ay + (a × d)' + az)
1 + # ax0 = # ay, unique_al(ax0), unique_al(ay), b ∈ ay, ∀ a0. a0 ∈ ax0 → a0 ∈ ay, ∀ ay0, b0. # ax0 = # ay0 ∧ unique_al(ay0) ∧ b0 ∈ ay0 ∧ (∀ a. a ∈ ax0 → a ∈ ay0) → b0 ∈ ax0, ∃ d, ay0, az. ay = ay0 + (a × d)' + az ⊦ b = a, a ∈ ax0, b ∈ ax0
Used terms: ay, a