| ⊦ count(a, bag0 \ ∅) = (count(a, ∅) < count(a, bag0) ⊃ count(a, bag0) - count(a, ∅);0) |
⊦ count(a, bag0) = (count(a, bag0) ≠ 0 ⊃ count(a, bag0);0)
Used simplifier rules: diff-empty: ⊦ bag0 \ ∅ = bag0;%sub-base: ⊦ m - 0 = m; from specification nat%zero: ⊦ 0 < m ↔ m ≠ 0; from specification nat-basic1%count-empty: ⊦ count(a, ∅) = 0; from specification bag-basic