| a ∈ (a0 ' + x0) -l b, ∀ a, b. a ∈ x0 -l b → a = b ∨ a ∈ x0 ⊦ a = b, a = a0, a ∈ x0 |
b = a0, a ∈ (a0 ' + x0) -l b, ∀ a, b. a ∈ x0 -l b → a = b ∨ a ∈ x0 ⊦ a = b, a = a0, a ∈ x0
a ∈ (a0 ' + x0) -l b, ∀ a, b. a ∈ x0 -l b → a = b ∨ a ∈ x0 ⊦ b = a0, a = b, a = a0, a ∈ x0
Used formulas: b = a0