| (mkbag(A, # A) -- A[m + 1] -- A[m + 2]) ++ A[m + 1] ++ b = mkbag(A0, # A0), m < # A, m + 2 < # A, m + 1 < # A ⊦ (mkbag(A, # A) -- A[m] -- A[m + 2]) ++ A[m] = (mkbag(A, # A) -- A[m + 1] -- A[m + 2]) ++ A[m + 1], A[m + 1] = A[m + 2], b = A[m + 2] |
⊦ bag -- a -- b = bag -- b -- a
(mkbag(A, # A) -- A[m + 1] -- A[m + 2]) ++ A[m + 1] ++ b = mkbag(A0, # A0), m + 1 < # A, m + 2 < # A, m < # A ⊦ (mkbag(A, # A) -- A[m + 2] -- A[m]) ++ A[m] = (mkbag(A, # A) -- A[m + 1] -- A[m + 2]) ++ A[m + 1], A[m + 1] = A[m + 2], b = A[m + 2]
Used terms: A[m + 2], A[m], mkbag(A, # A)