Example of Timeline Intervals

In the example of Joe, Mary and James's circumstances, we saw that Mary was not a lone parent of a minor before she married Joe, and that when she married Joe she was still not a lone parent of a minor, but for different reasons.

Under the hood here, when Mary's isLoneParentOfMinorTimeline value is being calculated, the input timelines which are used are Mary's isMarriedTimeline and her hasMinorDependentsTimeline.

CER identifies each date on which the input timelines change, for each of those dates calculates the resultant value (on that date) for whether Mary is a lone parent of a minor on that date, as follows:

Dates on which Mary's isMarriedTimeline changes:
- 1st January 2001; and
- 1st May 2004.
Dates on which Mary's hasMinorDependentsTimeline changes:
- 1st January 2001; and
- 1st June 2006.
Therefore dates on which one or more inputs changed are:
- 1st January 2001 (both of Mary's input timelines happen to change on this date); and
- 1st May 2004 (only Mary's isMarriedTimeline changes on this date); and
- 1st June 2006 (only Mary's hasMinorDependentsTimeline changes on this date).

So, for each of these dates, calculate the required value for isLoneParentOfMinorTimeline, using primitive Boolean/truth table logic:

Table 1. Calculation of interval values for Mary's `isLoneParentOfMinorTimeline` value
Date on which one or more input timelines changes value	Value of `isMarriedTimeline` on this date	Value of `hasMinorDependentsTimeline` on this date	Required value of `isLoneParentOfMinorTimeline` on this date
start of time (this date is always included)	FALSE	FALSE	FALSE
1st January 2001	TRUE	TRUE	FALSE
1st May 2004	FALSE	TRUE	TRUE
1st June 2006	FALSE	FALSE	FALSE

Finally, a timeline is constructed with the required values for isLoneParentOfMinorTimeline - at this point the construction of the timeline recognises that the value for start-of-time (FALSE) and 1st January 2001 (FALSE) are identical, and these intervals are merged into a single interval which stretches from the start of time up to (but not including) 1st May 2004 (when the value becomes TRUE).

Note: The resultant timeline has value changes on 1st May 2004 and 1st June 2006 only.

The timeline intentionally does not hold any record that 1st January 2001 was used during is construction, as the timeline's value did not change on that date - that date holds no relevance at all for the resultant timeline.