## Sibling-Disjoint Collections

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| Sets and Individuals in CYC®
| Collections of Collections
| Sibling-Disjoint Exceptions

A collection of collections is "sibling-disjoint" if it is an instance of #$SiblingDisjointCollection. (A more general but much less common collection is #$SiblingDisjointSetOrCollection.) If #$MyDisjointType is an instance of #$SiblingDisjointCollection, then each instance of #$MyDisjointType is mutually disjoint with all the other instances. In cases where the disjoining collection would have many instances, this is much more manageable and economical than making a large number of assertions involving #$disjointWith.

An exception to the disjoin is the case where one disjoined collection is a subset of another. In that case, a term may be an instance of both collections. Consider the following example:

The constant R may not be an instance of both A and B because A and B are both instances of #$MyDisjointType. S, however, may be an instance of both B and C, since (#$genls C B) is true.

#$DayOfWeekType is a good example of an instance of #$SiblingDisjointCollection. Its instances include terms like #$Friday and #$Saturday. Any particular day could be an instance of #$Friday or #$Saturday, but not both.

Last Update: 10/26/1998 11:41:18