∀ a, s. a ∈ x0 ∧ list2set(x0) ⊆ s → a ∈ s ⊦ a0 ∈ a + x0 ∧ list2set(a + x0) ⊆ s → a0 ∈ s
Used simplifier rules: list freely generated by [], +;;% ⊦ ¬ a ∈ [];