| ∀ a. rmdup(x0 + a ') = rmdup(x0 -l a) + a ' ⊦ (a0 ∈ x0 ⊃ rmdup(x0 + a ');a0 ' + rmdup(x0 + a ')) = rmdup(a0 ' + (x0 -l a)) + a ', a = a0 |
a0 ∈ x0, ∀ a. rmdup(x0 + a ') = rmdup(x0 -l a) + a ' ⊦ (a0 ∈ x0 ⊃ rmdup(x0 + a ');a0 ' + rmdup(x0 + a ')) = rmdup(a0 ' + (x0 -l a)) + a ', a = a0
∀ a. rmdup(x0 + a ') = rmdup(x0 -l a) + a ' ⊦ (a0 ∈ x0 ⊃ rmdup(x0 + a ');a0 ' + rmdup(x0 + a ')) = rmdup(a0 ' + (x0 -l a)) + a ', a = a0, a0 ∈ x0
Used formulas: a0 ∈ x0