| ⊦ dups(x), ∃ a. a ∈ x ∧ (a ∈ s ∨ a ∈ s0), (¬ a ∈ s ∨ ¬ a ∈ x) ∧ ¬ dups(x + set2list(s0)) |
⊦ dups(x + y) ↔ dups(x) ∨ dups(y) ∨ (∃ a. a ∈ x ∧ a ∈ y)
⊦ dups(x), ∃ a. a ∈ x ∧ (a ∈ s ∨ a ∈ s0), (¬ a ∈ s ∨ ¬ a ∈ x) ∧ ¬(dups(x) ∨ dups(set2list(s0)) ∨ (∃ a. a ∈ x ∧ a ∈ set2list(s0)))
Used terms: set2list(s0), x