Functional Reasoning, Explanation and Analysis: Qualitative Function Formation Technique

3 Functional Reasoning enables people to reason about the presence and function of components in a device, derive the purpose of the device and explain how it can be achieved. Qualitative Function Formation (QFF) a functional reasoning technique is introduced. Some novel points are extending the common qualitative models to include interactions and timing of events, by den-ing temporal and dependency constraints, and binding it with the conventional qualitative simulation. A function concept is dened as an interpretation of either a persistence or an order in the sequence of qualitative states, using the trace of the qualitative state vector derived by simulation on the extended qualitative model. QFF oers solution to the functional reasoning problems and is used to generalize and compare the functions of devices.