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  1. OMG Issue

DTV11 — Relationship between "equals" and "is"

  • Key: DTV11-100
  • Legacy Issue Number: 19417
  • Status: closed  
  • Source: Thematix Partners LLC ( Mr. Edward J. Barkmeyer)
  • Summary:

    In DTV Clause 8.2.3, in the entry for 'time interval1 equals time interval2', the second Note says:
    "SBVR uses the verb is for this relationship, but the equals relationship here is a specialization of 'thing is thing' for time intervals. Two time intervals are equal if they share particular properties of time interval, and the definition of equal does not involve properties that are suitable for a reference scheme."

    This relationship is important to business usage of the vocabulary. The SBVR formal mechanism for stating the first sentence is:
    General concept: 'thing1 is thing2'
    which makes the specialization clear. If two time intervals are equal, they are identical.
    One could also state it as a Necessity (with translations to CLIF and OCL):
    A time interval1 equals a time interval2 if and only if time interval1 is time interval2.
    which is actually a stronger (and correct) statement. It adds: if two time intervals are identical, they are necessarily equal.

    The second sentence of the Note is at best confusing, since reference schemes have nothing to do with equality. It should be deleted.

  • Reported: DTV 1.0 — Thu, 15 May 2014 04:00 GMT
  • Disposition: Resolved — DTV 1.1
  • Disposition Summary:

    This issue was discovered in an RTF discussion of another issue. The meeting agreed to the General concept and Necessity.

  • Updated: Fri, 6 Mar 2015 20:58 GMT