# ax0 = # ay0 + # az, unique_al(ay0 + (a × d)' + az), unique_al(ax0), a0 ∈ ax0, b ∈ ay0 ∨ b ∈ az, ∀ a0. a0 ∈ ax0 → a0 ∈ ay0 ∨ a0 ∈ az
⊦ b = a, b ∈ ax0, a ∈ ax0, a ∈ ay0, a ∈ az, a0 ∈ ay0, a0 ∈ az
User applied rule all left
And closed the goal!
Rule argument
pos: left 6 terms: a0 abort: F discard: T computed: F