DTV — Need to support infinite and indefinite time constructs

The Date Time Vocabulary needs to be able to support statements about periods of time which extend indefinitely into the future, and also describe periods of time which will have begun at indeterminate times in the past. As an example of the former, it is possible and meaningful for a contract to make statements about commitments or rights which extend in perpetuity, such as “Perpetual Bonds” which are bonds that pay interest forever.

In general, it is necessary to be able to make meaningful statements which embody the concept of “Forever”. Similarly, it is necessary to be able to make meaningful statements which have been going on in perpetuity up to the present time.

The DTV specification does currently allow for making statements about infinite time going forward, but not about time periods which have started at some indefinite time in the past. Meanwhile there are three other issues in play which touch on this same area. These may have an impact on the current ability to make statements about infinite time into the future as well, depending on their final resolution.

The issues which have a bearing or potential bearing on this matter are:

• Issue 16992: “Corollaries to Axiom D.4 in 8.2.3 are misstated”;
• Issue 16993: “no syntax for indefinite time periods (date-time-ftf)”;
• Issue 16997: “forever is misdefined”

In summary, the requirement that needs to be met with the resolution of this and the above-referenced issues is:

• Extend ‘forever’ with two new concepts:
  1. Indeterminate time in the past
  2. Indefinite time in the future

• Ensure that the concept “forever” can be adequately defined (per 16997) including with reference to the time axis;
• That there is syntax for the specification of indeterminate time periods that began at some point in the past and last up until the present (per 16993)
• That the restatement of the axiom and corollaries referenced in 16992 take account of the two concepts above (indeterminate time in the past and indefinite time in the future)

The FTF decided that there is no value in distinguishing ‘indefinite’ from ‘infinite’. It chose to add new concepts that provide the basis for time intervals that extend indefinitely into the past or the future.

New individual concepts ‘primordiality’ and ‘perpetuity’ are defined respectively as the occurrence interval of the earliest occurrence and of the latest occurrence. ‘Eternity’ (synonym ‘forever’) is defined as ‘primordiality through perpetuity’. This permits formulations such as “primordiality through today” and “2012 through perpetuity”. A tool might support these formulations with a syntax such as “… until today …” and “… from 2012 on …”.

Issue 16993 adds verb concepts such as ‘time interval until situation model’. ‘primordiality’ and ‘perpetuity’ can substitute for the ‘time interval’ role to enable formulations such as “primordiality until the Industrial Revolution”.

To support the definitions of these concept, two new verb concepts are added to clause 8.1.4, and an existing verb concept in 8.1.4 is renamed to avoid a name conflict.