Notes

Outline

Foundations of Knowledge Representation in Cyc Why use logic? CycL Syntax Collections and Individuals (#$isa and #$genls) Microtheories

Collections and Individuals A collection is a kind or class. Collections have instances. Each collection is characterized by some feature(s) that all of its instances share. Some collections #$Tower #$SpaceStation #$Director-Movie #$Person

Individuals An individual is a single thing, not a collection. Individuals do not have instances. Individuals may have parts. Some individuals: #$EiffelTower #$Mir #$OrsonWelles #$UnitedStatesMarineCorps

Joe The Marine #$UnitedStatesMarineCorps An individual organization A single, specific thing It has parts, but not instances

Remember... “Collections can have instances but not parts.” “Individuals can have parts but not instances.”

Everything Is An Instance of Something Every collection is, at minimum, an instance of #$Collection.

Collections of Collections and Collections of Individuals Some collections whose instances are individuals: #$Tower #$Person #$Dog Some collections whose instances are collections: #$ArtifactType #$Collection Some collections with instances of both types: #$ProprietaryConstant #$DocumentationConstant

Disjoint Collections Collections which have no instances in common are disjoint.

#$isa (#$isa X Y) means “X is an instance of collection Y.” (#$isa #$EiffelTower #$Tower) (#$isa #$Canada #$Country) (#$isa #$Cher #$Person) (#$isa #$UnitedStatesMarineCorps #$ModernMilitaryOrganization)

#$genls (#$genls X Y) means “Every instance of collection X is also an instance of collection Y.” (#$genls #$Dog #$Mammal) (#$genls #$Tower #$FixedStructure) (#$genls #$ModernMilitaryOrganization #$Organization)

#$genls is transitive

The #$genls hierarchy

#$isa is NOT transitive

Remember . . . Because every instance of a collection is also an instance of the collection’s genls,  the following statements are true: “#$isa transfers through #$genls.” “#$isa does NOT transfer through #$isa.”

What can we conclude about #$Rover the dog?

A more complete list of collections of which #$Rover is an instance #$Agent-Generic #$Agent #$AirBreathingVertebrate   #$Animal   #$AnimalBLO  #$BilateralObject   #$BiologicalLivingObject   #$CanineAnimal   #$Carnivore  #$CompositeTangibleAndIntangibleObject   #$Dog   #$Eutheria #$Individual #$IndividualAgent  #$LeftAndRightSidedObject   #$Mammal   #$NaturalTangibleStuff  #$NonPersonAnimal   #$OrganicStuff   #$Organism-Whole  #$PartiallyIntangible   #$PartiallyIntangibleIndividual   #$PartiallyTangible  #$PerceptualAgent   #$SentientAnimal   #$SomethingExisting  #$SpatialThing   #$SpatialThing-Localized   #$TemporalThing   #$Thing #$Vertebrate

Is #$genls reflexive? Consider (#$genls #$Dog #$Dog) This means

Is #$isa reflexive? Consider (#$isa #$Dog #$Dog)

Summary Collections vs. Individuals #$isa vs. #$genls #$genls is transitive #$genls is reflexive