To test for this cooccurrence, we extend the definition of cooccurrence to apply to mixed node and event arguments.
c(N, E) or c(E, N ) is the number of times node N cooccurred in the training data with any node from event E. The order in which the arguments are given is the order in which An example of two nodes (N 2 and N 3 ) that meet our two criteria is given in Figure 3.