This paper gives an O(n log n) bound-consistency filtering algorithm for the conjunction alldifferent(V0,V1,…,Vn−1)∧ f(V0)⌖f(V1)⌖…⌖f(Vn−1) ≤ cst, (V0,V1,…,Vn−1,cst ∊ N+), where (N,⌖) is a commutative group, f is a unary function, and both ⌖ and f are monotone increasing. This complexity is equal to the complexity of the bound-consistency algorithm of the alldifferent constraint.