A.3.3.CC:2 - Problem

Separate value ranges leave relations unstated. Each endpoint of a rigid link can have a position in a plane, yet most pairs of positions violate the link length. A software representation that permits every pair will include arrangements the intended physical model excludes.

A reduced description can fail in the opposite direction. One buffer count determines the other while total stock is fixed. After external arrivals become possible, keeping that same formula excludes distributions the new situation permits. Counts can also lose job order when the question changes from occupancy to which job is served next.

The construction must therefore retain the differences relevant to the question, express the constraints between them and provide a way to interpret the represented combinations. The choice of variables and the choice of constraints have to be made together.