Editing CycL (section)

=== Constants ===
The concept names in Cyc are known as ''constants''. Constants start with "#$" and are case-sensitive. There are constants for:
* Individual items known as ''individuals'', such as #$BillClinton or #$France. 
* ''Collections'', such as #$Tree-ThePlant (containing all trees) or #$EquivalenceRelation (containing all [[equivalence relation]]s). A member of a collection is called an ''instance'' of that collection.
* ''Truth Functions'' which can be applied to one or more other concepts and return either true or false. For example, #$siblings is the sibling relationship, true if the two arguments are siblings. By convention, truth function constants start with a lower-case letter.  Truth functions may be broken down into logical connectives (such as #$and, #$or, #$not, #$implies), quantifiers (#${{not a typo|forAll}}, #${{not a typo|thereExists}}, etc.) and predicates.
* ''Functions'', which produce new terms from given ones. For example, #$FruitFn, when provided with an argument describing a type (or collection) of plants, will return the collection of its fruits. By convention, function constants start with an upper-case letter and end with the string "Fn".