| ⊦ count(a, bag1) ≠ 0 → ((∀ a0. count(a0, bag0) ≤ count(a0, bag1 -- a)) ↔ bag0 ++ a ⊆ bag1) |
⊦ count(a, bag1) = 0, (∀ a0. count(a0, bag0) ≤ count(a0, bag1) - (a0 = a ⊃ 1;0)) ↔ bag0 ++ a ⊆ bag1
Used simplifier rules: count-del: ⊦ count(a, bag -- b) = count(a, bag) - (a = b ∧ count(a, bag) ≠ 0 ⊃ 1;0);