 For a multivariate function formula_1, functional decomposition generally refers to a process of identifying a set of functions formula_2 such that

where formula_4 is some other function.Thus, we would say that the function formula_5 is decomposed into functions formula_2.This process is intrinsically hierarchical in the sense that we can (and often do) seek to further decompose the functions formula_7 into a collection of constituent functions formula_8such that

where formula_10 is some other function.