Before revision:  We argue that the mutual information (MI) between a  subset of the inputs X = {X_1, ..., X_n} of  node i and the function f_i(X) associated with node i quantifies the determinative power of this subset of inputs over node i.
After revision:  We argue that the mutual information (MI) between a given subset of the inputs X = {X_1, ..., X_n} of node i and the function f_i(X) associated with node i quantifies the determinative power of this subset of inputs over node i.