Embodiments of a computer-implemented method of calculating estimates of a joint posterior probability of class membership given combinations of attribute values of a pair of attributes are disclosed. This allows the introduction of a high gradient magnetic field to effectively magnetize both the weakly and strongly magnetic particulates for subsequent removal by setting or other techniques. The other nodes then respond by setting up communications information enabling the new node to directly communicate with a monitor process in the responding nodes and sending that information to the new node.