Uses of #$genls and #$isa
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Every CYC® constant is an element of at least one collection. In
fact, everything that can appear in a CYC® expression is an element of
some collection. Every collection, with the exception of #$Thing, is
a subset of at least one other collection. These subset and instance
of relations, expressed with assertions using #$genls and
#$isa, make up the basic framework of the CYC® KB.
Heres a diagram showing some hypothetical constants and the #$genls and
#$isa relations between them:

In this diagram, we introduce some conventions which will be used
throughout the CYC® documentation:
- CYC® constants are represented as text in rectangular boxes.
- A constant with blue text denotes a collection.
- A constant with green text denotes an individual.
- Constants which could be either a collection or an individual are
shown with black text.
- Assertions involving binary predicates are shown as lines between constants.
- #$isa assertions are shown as green lines.
- #$genls assertions are shown as blue lines.
- An abbreviation for the predicate in a binary assertion is placed near the
middle of the line, using red text. A key to the abbreviations is included
in the diagram.
- More general collections are placed higher on the page than their subsets.
- Collections are placed higher on the page than their instances.
The diagram therefore indicates the following assertions:
(#$isa A #$Collection)
(#$isa B #$Collection)
(#$isa C #$Collection)
(#$genls A #$Individual)
(#$genls B #$Individual)
(#$genls C B)
(#$isa S C)
(#$isa R A)
(#$isa R B)
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Last Update: 10/26/1998 11:41:21