⊦ a ≠ b → count(a, bag ++ b) = count(a, bag)
Used simplifier rules: ⊦ count(a, ∅) = 0; (s)% ⊦ ¬ m < 0; (s)% ⊦ count(a, ∅ ++ a) = 1; (s)% ⊦ m < 1 ↔ m = 0; (s) Used terms: a, ∅, a0