| a ∈ bag ⊦ (a0 = a ⊃ 1;0) + (count(a0, bag) - (a0 = a ∧ count(a, bag) ≠ 0 ⊃ 1;0)) = count(a0, bag) |
a0 = a, a ∈ bag ⊦ 1 + (count(a0, bag) - (a0 = a ∧ count(a, bag) ≠ 0 ⊃ 1;0)) = count(a0, bag)
Used simplifier rules: ⊦ m - 0 = m; (s)% ⊦ n + 0 = n; (s)%a: ⊦ (m + n0) + n1 = m + n0 + n1; from specification nat-basic%c: ⊦ m + n = n + m; from specification nat-basic