| P(H) ⊦ r = null, r ∈ H, ∃ H0, H1. H0 ⊥ H1 ∧ H ++ r = H0 ∪ H1 ∧ ((r => (H ++ r)[r]))(H0) ∧ P(H1) |
P(H) ⊦ r = null, r ∈ H, ∃ H1. ¬ r ∈ H1 ∧ H ++ r = (∅ ++ r)[r, (H ++ r)[r]] ∪ H1 ∧ P(H1)
Used simplifier rules: maplet: ⊦ ((r => o))(H) ↔ H = (∅ ++ r)[r, o] ∧ r ≠ null;%r ≠ null ⊦ (∅ ++ r)[r, o] ⊥ H ↔ ¬ r ∈ H; (s)