Functional requirements decomposition in set-based design

TL;DR

This paper introduces a four-step hierarchical method for decomposing functional requirements in set-based design, aiding early-stage complex systems development by formalizing the decomposition process.

Contribution

It provides the first formal, systematic approach to functional requirements decomposition specifically tailored for set-based design in complex systems.

Findings

The method enables systematic decomposition of requirements.

It supports parallel abstraction to ensure top-level requirement satisfaction.

The approach formalizes a previously informal process.

Abstract

Designing systems is typically uncertain and ambiguous at early stages. Set-based design supports alternative exploration and gradual uncertainty reduction during the early lifecycle, making it practical for complex systems design. In parallel, the functional requirements decomposition helps to advance the design incrementally. However, current literature on set-based design lacks formal guidance in how to decompose functional requirements. To bridge this gap, we introduce a four-step method to decompose functional requirements for set-based design hierarchically. We systematically define, reason, and narrow the sets, breaking down the functional requirements into formal sub-requirements. This method allows parallel abstraction, ensuring the resulting system satisfies the top-level functional requirements.