Summary
In this chapter, we dealt with duration management. The discussion started with one timepoint modeling expressing the validity. This solution is strongly limited by the efficiency of data storage and subsequent data processing because many duplicate tuples can be present. However, by changing its meaning, the duration can be modeled. Namely, the timepoint can represent the beginning point of the validity. Thanks to that, each new state of the object automatically limits the validity of the direct predecessor. Valid future states can also be covered. There is, however, one strong limitation related to completely undefined states, which cannot be modeled, and special notation must be introduced.
Therefore, a general solution is provided by two timepoints representing the begin and end points of the validity duration frame. They can have various representations based on whether the begin and end points of the duration interval are part of the validity or not. The most often...
