Functional decomposition is a technique that breaks down a complex solution scope into smaller and manageable work products or deliverables. It helps to understand the scope of work that needs to be completed, and to organize and prioritize the requirements. Functional decomposition can be represented in various ways, such as hierarchical diagrams, tables, or lists. It can also be used to create a work breakdown structure (WBS) for the project management. Functional decomposition is useful for projects that have a large or unclear solution scope, as it helps to reduce ambiguity and complexity, and to identify dependencies and gaps. References:

Using Scope Models to Manage Solution Scope

Solution Scope vs. Project Scope

Solution Scope – An Insight