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