| count(m, bag) = 0, ∀ n. count(n, bag) ≤ 1 ⊦ count(n, bag ++ m) = 0, count(n, bag ++ m) = 1 |
⊦ count(n, bag0 ++ n0) = (n = n0 ⊃ 1;0) + count(n, bag0)
count(m, bag) = 0, ∀ n. count(n, bag) ≤ 1 ⊦ (n = m ⊃ 1;0) + count(n, bag) = 1, (n = m ⊃ 1;0) + count(n, bag) = 0
Used terms: m, bag, n