  As interdisciplinary science is flourishing because of materials informatics
and additional factors; a systematic way is required for expressing knowledge
and facilitating communication between scientists in various fields. A function
decomposition tree is such a representation, but domain scientists face
difficulty in constructing it. Thus, this study cites the general problems
encountered by beginners in generating function decomposition trees and
proposes a new function decomposition representation method based on a
causality-first perspective for resolution of these problems. The
causality-first decomposition tree was obtained from a workflow expressed
according to the processing sequence. Moreover, we developed a program that
performed automatic conversion using the features of the causality-first
decomposition trees. The proposed method was applied to materials informatics
to demonstrate the systematic representation of expert knowledge and its
usefullness.
