| r ∈ H ⊦ ∃ H0, o. H = H0 ∪ (∅ ++ r)[r, o] ∧ ¬ r ∈ H0 |
⊦ r ≠ null → (r ∈ H ↔ (∃ H0, o. H = (H0 ++ r)[r, o] ∧ ¬ r ∈ H0))
∃ H0, o. H = (H0 ++ r)[r, o] ∧ ¬ r ∈ H0 ⊦ r = null, ∃ H0, o. H = H0 ∪ (∅ ++ r)[r, o] ∧ ¬ r ∈ H0
Used simplifier rules: sanity: ⊦ ¬ null ∈ H; Used terms: H, r