Example 2.5 [Bottle–can Opener] (NSF 1998, Suh 1999)
Suppose we need a device that can open bottles and cans. Functional requirements
are defined as follows:
FR1 : Design a device that can open bottles.
FR2 : Design a device that can open cans.
Solution
The device in Figure 2.9 has one physical entity for the bottle opener and can
opener. However, two DPs at both ends independently satisfy the two functional
requirements. Therefore, the design in Figure 2.9 satisfies the Independence
Axiom. If the constraint set includes “both functions should be simultaneously
used,” then a different design should be investigated.