| ∀ n. (∀ n0. count(n0, (bag0 -- n) ++ n) = count(n0, bag0)) ↔ count(n, bag0) ≠ 0 ⊦ count(n, bag0) = 0, count(n0, bag0 -- n) = count(n0, bag0), n = m, n0 = n, n0 = m |
⊦ count(n, bag0 -- n0) = count(n, bag0) - (n = n0 ∧ count(n, bag0) ≠ 0 ⊃ 1;0)
Used simplifier rules: ⊦ m - 0 = m; (s) Used terms: n, bag0, n0