Table 1 Classes of modeling assumption constraints (from structural viewpoint)

MAC

Physical structure constraint (PSC)

Decision about the perspective and granularity in modeling

Physical object constraint (PO)

Specifies what kind of objects in a physical system are considered

- Consider two blocks in contact as they are or as one

- Consider two parallel-connected springs/resistors as they are or a compound one

Physical attribute constraint (PA)

Specifies what kind of relations/attributes of objects in a physical systems are considered

- Consider a block’s net-force or its electric resistance

- Consider the friction between two objects in contact or not

Operating range constraint (ORC)

Decision about the behavioral range of the model

Physical range constraint (PR)

Specifies the range (state space) within which the model is valid by using physical attributes

- A model of two blocks’ motion where one pulls another thru a string assuming the string is taut

- A model of a constant resistance assumes its current and voltage are within the proportional range

Conceptual range constraint (CR)

Specifies the range (state space) within which the model is valid by using conceptual attributes

- A model of a block (b) descending a slope (p) by gravity from the gravitational field (g) assuming their positional relations are in (b, g), on (b, p)