SBVR11 — Set requires distinguished things

Clause 8.7 introduces the idea of set and cardinality in order to support 'at least n' and 'at most n' constraint concepts. 'set' is defined to be an unordered collection of zero or more things. Marking 'set' a formal logic concept "FL" raises the issue of identity of things. Cardinality of a set is defined as "the number of distinct elements in the set, The definition of 'set' should also refer to 'distinct' or 'distinguished' things. The ability to distinguish makes it possible to determine the truth value of 'thing is in set' for an arbitrary thing.

The 'set' entry should probably also include a Note, such as:
Note: The means of distinguishing things as elements of a set is dependent on the kind of thing and the viewpoint taken in constructing each kind of set. Reference schemes may be used in this regard. Where the SBVR specification defines concepts that are 'sets', the defined reference scheme is used to distinguish elements.

The issue of distinguishing elements of a set is complex. The easier solution is the one chosen in clause 10, to define a set as a collection of things “without regard to ordering or repetition”.
The definition of cardinality will be corrected to match the definition of ‘set has cardinality’, and a form of the recommended Note will be added.