Abstract: Given a totally or partially defined Boolean function f(x₁,…, x_n), the problem that under what conditions f(x₁,…, x_n)=g((x₁,…, x_is)·h(x_j,…, x_t), where sets {i₁,…, i_s} and {j₁,…, j_t} are a partition of set {1,…,n}, is very interesting and important. Two decomposition methods are presented in this paper. They are suitable for the totally or partially denned Boolean function which is represented by an expression or a truth table, respectively.

Key words: cut, partition, expansion, Boolean function