| P(H) ⊦ H ++ r = (∅ ++ r)[r, (H ++ r)[r]] ∪ H, r = null, r ∈ H |
⊦ H0 = H1 ↔ (∀ r. (r ∈ H0 ↔ r ∈ H1) ∧ (r ∈ H0 → H0[r] = H1[r]))
P(H) ⊦ r = null, r ∈ H, ∀ r0. (r0 ∈ H ++ r ↔ r0 ∈ (∅ ++ r)[r, (H ++ r)[r]] ∪ H) ∧ (r0 ∈ H ++ r → (H ++ r)[r0] = ((∅ ++ r)[r, (H ++ r)[r]] ∪ H)[r0])
Used terms: (∅ ++ r)[r, (H ++ r)[r]] ∪ H, H ++ r