| unique_al(ax0 -1l (a0 × d0)), unique_al(ax0), a ∈ ax0 ⊦ a0 × d0 = a × d, a0 = a, a ∈ ax0 -1l (a0 × d0), a0 ∈ ax0 -1l (a0 × d0) |
⊦ a ∈ ax ↔ (∃ d. a × d ∈ ax)
unique_al(ax0 -1l (a0 × d0)), unique_al(ax0), ∃ d. a × d ∈ ax0 ⊦ a0 × d0 = a × d, a0 = a, a ∈ ax0 -1l (a0 × d0), a0 ∈ ax0 -1l (a0 × d0)
Used terms: ax0, a