ABSTRACT. We discuss a stochastic operator method in ergodic theory and its application to the well-known Rokhlin higher-order mixing problem. In this paper invariants of dynamical systems which guarantee multiple mixing property are considered. These invariants, which are expressed in terms of operators intertwining Cartesian products of systems, are some analogs of known properties of joinings. A typical result: any mixing flow (an action of the group R n) with a simple stochastic centralizer is mixing of all orders.