INTERSECTION
- Last Updated: May 13, 2026
- 2 minute read
- Semaphore
- Documentation
The INTERSECTION rule will fire if there is any intersection between the evidence of all of its child rules.
Score calculation
Scores its given weight if any evidence intersects
Evidence calculation
The evidence is the intersection of its children’s evidence
Attribute information
Children restrictions
Any rule other than those restricted to a specific parent
This rule behaves like a mathematical intersection of sets.
In most cases it is expected that this will be used for preclusion rules where the containing phrase is notted but the rule will work for other types of intersection.
However sometimes the results of using this rule in a non preclusion idiom are surprising at first glance. This is because the rule is considering the intersection between sets of phrase ranges. Phrase ranges can “intersect” by overlapping as well as the simple case of being identical.
Handling the nuances of partial overlap creating an intersection is why there are both an intersect and a select rule and care needs to be taken to use the appropriate rule for your use case.
Example
<intersection>
<phrase not="1" data="chief executive officer" />
<text data="executive"/>
</intersection>

This is showing our frequent preclusion style use of this operator
If all our occurrences of “chief executive officer” in the document are in the left hand set - all occurrences of “executive” are in the right then the rule will fire only if the red coloured area is not empty (and the foreach count will be the count of occurrences in this red area)