| unique-elems(bag) ⊦ count(m, bag -- n) = 0, m ≠ n ∧ m ∈ bag |
⊦ count(n, bag0 -- n0) = count(n, bag0) - (n = n0 ∧ count(n, bag0) ≠ 0 ⊃ 1;0)
unique-elems(bag) ⊦ count(m, bag) - (m = n ∧ count(m, bag) ≠ 0 ⊃ 1;0) = 0, m ≠ n ∧ m ∈ bag
Used terms: n, bag, m