| count(a, bag0 ++ a0) = 0, ∀ a. count(a, bag0) = 0 → bag0 -- a = bag0 ⊦ (bag0 ++ a0) -- a = bag0 ++ a0 |
count(a, bag0 ++ a0) = 0, ∀ a. count(a, bag0) = 0 → bag0 -- a = bag0 ⊦ (a0 = a ⊃ bag0;(bag0 -- a) ++ a0) = bag0 ++ a0
Used simplifier rules: del-rec: ⊦ (bag ++ a) -- b = (a = b ⊃ bag;(bag -- b) ++ a);