1. In a machine-effected method of updating a pattern-matching network having a plurality of pattern-matching nodes which are logically interconnected in logic paths so that argument inputs to the nodes come from diverse predecessor ones of the nodes; including the machine-executed steps of: at a predetermined one of said nodes, passing a change token from a set of predecessor nodes to a first input of said one node for updating same; at a predecessor node logically connected to a second input of said predetermined one of said nodes, storing a plurality of pattern match tokens; for each test to be conducted, indicating whether or not the change token may result in changing values during test interation in a test to be conducted; examining the node for tests to be conducted between the change token and partial match tokens available to said second input, if no tests are to be conducted, then proceeding to other machine operations, otherwise; if the indication shows no changing values during said one test, computing the change token value for a first iteration of the test and caching the computed change token value for said one node and using the cached value for ensuing iterations of said one test, otherwise computing the change token argument value at each iteration of said one test.