]> 2008/06/10 OpenCyc Knowledge Base Copyright© 2001-2008 Cycorp, Inc., http://www.cyc.com/, Austin, TX, USA This file contains an OWL representation of information contained in the OpenCyc Knowledge Base. The content of this OWL file is licensed under the Creative Commons Attribution 3.0 license whose text can be found at http://creativecommons.org/licenses/by/3.0/legalcode. The content of this OWL file, including the OpenCyc content it represents, constitutes the "Work" referred to in the Creative Commons license. The terms of this license equally apply to, without limitation, renamings and other logically equivalent reformulations of the content of this OWL file (or portions thereof) in any natural or formal language, as well as to derivations of this content or inclusion of it in other ontologies. externalID A unique, language-neutral, variable-sized identifier for a concept that can be used to refer unambiguously to that concept across OWL exports or across Cyc inference engines. label A natural-language representation for a concept that is both human readable and readable by the Cyc inference engine. These terms are not guaranteed to refer to the same concept across time but are guaranteed to be consistent within a particular OWL export. Use 'cycAnnot:externalID' for unambiguously referring to a concept across OWL exports or across Cyc inference engines. empty collection A collection of collections and a specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv1ZxY5wpEbGdrcN5Y29ycA" class="cyc_term">EmptySetOrCollection</a> (q.v.). A collection is an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rDKZQEKVnQdmACrINeAfsGw" class="cyc_term">EmptyCollection</a> if and only if it has no instances. <p/> Some collections are by their very nature necessarily empty; e.g. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv7LKYpwpEbGdrcN5Y29ycA" class="cyc_term">Nothing</a> (q.v.). Conversely, some collections are empty in some contexts and non-empty in others; e.g. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvhn_I5wpEbGdrcN5Y29ycA" class="cyc_term">Unicorn</a> might be empty in the context of the actual world but non-empty in certain mythological contexts. Similarly, a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwIE23ZwpEbGdrcN5Y29ycA" class="cyc_term">TimeDependentCollection</a> might be empty at certain times and non-empty at certain other times; e.g. the collection of female US presidents is currently empty but will hopefully become non-empty some time in the near future. This last example demonstrates that <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rDKZQEKVnQdmACrINeAfsGw" class="cyc_term">EmptyCollection</a> is itself a time-dependent collection. <p/> Note that each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rDKZQEKVnQdmACrINeAfsGw" class="cyc_term">EmptyCollection</a> is <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViA45wpEbGdrcN5Y29ycA" class="cyc_term">disjointWith</a> (q.v.) every collection -- including itself. <p/> Cf. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r_3mf2qedQdmNjeDW39lDKA" class="cyc_term">NonEmptyCollection</a>. EmptyCollection The collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjK65wpEbGdrcN5Y29ycA" class="cyc_term">BiologicalSpecies</a> and other <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjf5JwpEbGdrcN5Y29ycA" class="cyc_term">OrganismClassificationType</a>s that are extinct. Extinct-OrganismTypeByExistentialThreatLevel extinct member of { urban neighbourhoods, groups of office buildings } (CollectionIntersectionFn (TheSet UrbanNeighborhood (GroupFn OfficeBuilding))) abandoned township (CollectionIntersectionFn (TheSet Abandoned-ExistentialStatus Town)) InternetNewsgroup newsgroup The collection of all internet newsgroups, such as rec.music.makers or alt.food.preserving. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwRZ4-pwpEbGdrcN5Y29ycA" class="cyc_term">InternetNewsgroup</a> has as <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv6HodJwpEbGdrcN5Y29ycA" class="cyc_term">episodes</a> instances of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv9-EFpwpEbGdrcN5Y29ycA" class="cyc_term">InternetNewsgroupMessage</a>, each of which is more or less on the group's central topic of focus. (CollectionIntersectionFn (TheSet Soldier SelfEmployedWorker)) soldier of fortune An instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rDKZQEKVnQdmACrINeAfsGw" class="cyc_term">EmptyCollection</a> (q.v.). <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv7LKYpwpEbGdrcN5Y29ycA" class="cyc_term">Nothing</a> is in effect the collection-theoretical complement of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViA9JwpEbGdrcN5Y29ycA" class="cyc_term">Thing</a> (q.v.): the necessarily empty collection that is by definition equal to (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwTvAxJwpEbGdrcN5Y29ycA" class="cyc_term">rewriteOf</a>) (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwROrhZwpEbGdrcN5Y29ycA" class="cyc_term">CollectionDifferenceFn</a> <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViA9JwpEbGdrcN5Y29ycA" class="cyc_term">Thing</a> <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViA9JwpEbGdrcN5Y29ycA" class="cyc_term">Thing</a>). non-thing Nothing mechanized infantry brigade The collection of all <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rLvHKZDt6EdaAAACgye-oRQ" class="cyc_term">Brigade_MilitaryEchelon</a> level <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvXDlS5wpEbGdrcN5Y29ycA" class="cyc_term">MechanizedInfantryUnit_MilitarySpecialty</a>. MechanizedInfantryBrigade (CollectionIntersectionFn (TheSet CoastalRegion Village)) member of { coastal regions, villages } (NationalForestsInFn Connecticut-State) national forest in Connecticut InternetNewsgroupMessage A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvq7pm5wpEbGdrcN5Y29ycA" class="cyc_term">Letter_CW</a>. Each instance of this collection is an individual posting to some <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwRZ4-pwpEbGdrcN5Y29ycA" class="cyc_term">InternetNewsgroup</a>. newsgroup message ContactLens contact lens The collection of all contact lenses. A type of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVkEoJwpEbGdrcN5Y29ycA" class="cyc_term">SomethingToWear</a>, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv2li2pwpEbGdrcN5Y29ycA" class="cyc_term">Eyewear</a>, and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvbddiJwpEbGdrcN5Y29ycA" class="cyc_term">Lens_Artificial</a>. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjkK5wpEbGdrcN5Y29ycA" class="cyc_term">ContactLens</a> is a small lens designed to be worn in direct contact with the eye. incandescent bulb A bulb of glass or quartz enclosing material that incandesces or fluoresces when provided with current, thus generating light. LightBulbIncandescent mechanized infantry unit battalion MechanizedInfantryUnitBat-MilitarySpecialty Salyut salyut The collection of all Salyut <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvb36jJwpEbGdrcN5Y29ycA" class="cyc_term">SpaceStation</a>s. The first <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwAYN2JwpEbGdrcN5Y29ycA" class="cyc_term">Salyut</a>, Salyut I, was the first <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvb36jJwpEbGdrcN5Y29ycA" class="cyc_term">SpaceStation</a> constructed by humanity. The <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjPzpwpEbGdrcN5Y29ycA" class="cyc_term">UnionOfSovietSocialistRepublics</a> launched seven of such craft, the first on 19 April 1971, and the last in 1982. ApolloSpacecraft Apollo The collection of all Apollo manned <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwQtlDpwpEbGdrcN5Y29ycA" class="cyc_term">Spacecraft</a>. Each <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvpFmspwpEbGdrcN5Y29ycA" class="cyc_term">ApolloSpacecraft</a> could transport three <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViddZwpEbGdrcN5Y29ycA" class="cyc_term">Astronaut</a>s to Earth orbit. Several <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvpFmspwpEbGdrcN5Y29ycA" class="cyc_term">ApolloSpacecraft</a> went to the moon (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjWEZwpEbGdrcN5Y29ycA" class="cyc_term">MoonOfEarth</a>). Gemini GeminiSpacecraft The collection of all Gemini manned <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwQtlDpwpEbGdrcN5Y29ycA" class="cyc_term">Spacecraft</a>. Each <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwMVUlJwpEbGdrcN5Y29ycA" class="cyc_term">GeminiSpacecraft</a> could transport two <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViddZwpEbGdrcN5Y29ycA" class="cyc_term">Astronaut</a>s to Earth orbit. A television set TelevisionSet television set (CollectionIntersectionFn (TheSet RuinedArtifact Town)) member of { ruins, townships } frigate A collection. Warships which are larger than destroyers and smaller than cruisers. ModernFrigate The collection of all Mercury manned <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwQtlDpwpEbGdrcN5Y29ycA" class="cyc_term">Spacecraft</a>. Each <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv5kRqpwpEbGdrcN5Y29ycA" class="cyc_term">MercurySpacecraft</a> could transport one <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViddZwpEbGdrcN5Y29ycA" class="cyc_term">Astronaut</a>s out of Earth's atmosphere. The first two flights were suborbital, the last five were orbital. Mercury MercurySpacecraft sailing frigate Frigate-SailingShip record player RecordPlayer A device used to play phonograph records space station SpaceStation The collection of spacecraft intended to remain in orbit for a relatively long period of time, with personnel being transported between <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVkL_pwpEbGdrcN5Y29ycA" class="cyc_term">PlanetEarth</a> and the space station via a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViUfJwpEbGdrcN5Y29ycA" class="cyc_term">SpaceShuttle</a> or similar vehicle. Satellite-Device A man-made device intended to orbit a celestial body (for most of them, Earth). satellite bifocals The collection of all bifocals. A type of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rzJFlWvBAQdeFE7-eA63azA" class="cyc_term">Eyewear_Corrective</a>. The collection <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwG1I9pwpEbGdrcN5Y29ycA" class="cyc_term">Bifocals</a> is an <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rejmDbrF_QdeIENT1qpbYzQ" class="cyc_term">ArtifactTypeByGenericCategory</a> and a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rpPHhAOB1EdqAAAACs6hRXg" class="cyc_term">SpatiallyDisjointObjectType</a>. Bifocals internal organ A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvcbbL5wpEbGdrcN5Y29ycA" class="cyc_term">InternalAnatomicalPart</a>. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvvwMaJwpEbGdrcN5Y29ycA" class="cyc_term">InternalOrgan</a> is the collection of all organs (see the collection <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwP3iWpwpEbGdrcN5Y29ycA" class="cyc_term">Organ</a>) that are also instances of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvcbbL5wpEbGdrcN5Y29ycA" class="cyc_term">InternalAnatomicalPart</a>. Specializations of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvvwMaJwpEbGdrcN5Y29ycA" class="cyc_term">InternalOrgan</a> include <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVimppwpEbGdrcN5Y29ycA" class="cyc_term">Liver</a>, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjlqpwpEbGdrcN5Y29ycA" class="cyc_term">Stomach</a>, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjvDpwpEbGdrcN5Y29ycA" class="cyc_term">Heart</a>, and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjT65wpEbGdrcN5Y29ycA" class="cyc_term">Brain</a>. InternalOrgan Tae Bo The collection of all events of performing the 'Tae Bo' form of exercise. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwNY2gpwpEbGdrcN5Y29ycA" class="cyc_term">TaeBoExercising</a> was invented in the 1990's by an American <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvkiRVJwpEbGdrcN5Y29ycA" class="cyc_term">BillyBlanks</a> inspired by Asian martial arts techniques, and it was heavily promoted on American television as a commercial program. TaeBoExercising OuijaSet a device consisting of a small board, or planchette, on legs that rest on a larger board marked (typically) with the letters of the alphabet arranged in two curved rows, the numerals 1-0 in a row under the letters, the words 'yes' and 'no' in the upper corners, and the phrase 'good bye' at the bottom. Typically, two people sit facing each other and place their fingers on the planchette, which eventually begins to move and point to letters, numbers, etc. on the larger board, spelling out a (possibly cryptic) message or answer to a question. Ouija sets were invented and patented in the U.S. around 1890. Parker Bros. currently owns the rights and manufactures ouija sets. Ouija set Chimney The collection of chimneys, vertically-oriented portals that serve to direct hot or dangerous gases to an outdoor location, either by acting as a flue (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r6GZWLC-HEdqAAAACs71DGQ" class="cyc_term">Flue</a>) or (as with most modern home chimneys (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVj2g5wpEbGdrcN5Y29ycA" class="cyc_term">Chimney_HousePart</a>)) by serving as a rigid, protective (and often decorative) structure that contains the final part of the flue. chimney soldier of fortune (InstanceNamedFn-Ternary "mercenary" PersonTypeByOccupation "48952ed6-17b2-41d9-86f6-9dd5adb5736d") Hovercraft air cushion vehicle The collection of vehicles which ride above the surface of the water on a cushion of air, usually provided by fans. A collection of collections of collections. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvtppU5wpEbGdrcN5Y29ycA" class="cyc_term">CollectionType</a> is the collection of all (and only) types of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViAzJwpEbGdrcN5Y29ycA" class="cyc_term">Collection</a>s. More precisely, a thing COLLTYPE is an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvtppU5wpEbGdrcN5Y29ycA" class="cyc_term">CollectionType</a> if and only if COLLTYPE is a non-empty collection all of whose instances are collections. Example: <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwPzQbJwpEbGdrcN5Y29ycA" class="cyc_term">PersonTypeByCulture</a>, each of whose instances is the collection of all persons who participate in some particular human culture, is an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvtppU5wpEbGdrcN5Y29ycA" class="cyc_term">CollectionType</a>. Important specializations of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvtppU5wpEbGdrcN5Y29ycA" class="cyc_term">CollectionType</a> include <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvWPoRpwpEbGdrcN5Y29ycA" class="cyc_term">DisjointCollectionType</a>, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViA4pwpEbGdrcN5Y29ycA" class="cyc_term">SiblingDisjointCollectionType</a>, and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rviPYH5wpEbGdrcN5Y29ycA" class="cyc_term">CollectionTypeType</a>. CollectionType type of collection cardinality of 0 A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvf-kupwpEbGdrcN5Y29ycA" class="cyc_term">SetOrCollectionTypeByCardinality</a> for object types that have no instantiations. EmptySetOrCollection empty collection A collection of collections and a specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv1ZxY5wpEbGdrcN5Y29ycA" class="cyc_term">EmptySetOrCollection</a> (q.v.). A collection is an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rDKZQEKVnQdmACrINeAfsGw" class="cyc_term">EmptyCollection</a> if and only if it has no instances. <p/> Some collections are by their very nature necessarily empty; e.g. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv7LKYpwpEbGdrcN5Y29ycA" class="cyc_term">Nothing</a> (q.v.). Conversely, some collections are empty in some contexts and non-empty in others; e.g. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvhn_I5wpEbGdrcN5Y29ycA" class="cyc_term">Unicorn</a> might be empty in the context of the actual world but non-empty in certain mythological contexts. Similarly, a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwIE23ZwpEbGdrcN5Y29ycA" class="cyc_term">TimeDependentCollection</a> might be empty at certain times and non-empty at certain other times; e.g. the collection of female US presidents is currently empty but will hopefully become non-empty some time in the near future. This last example demonstrates that <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rDKZQEKVnQdmACrINeAfsGw" class="cyc_term">EmptyCollection</a> is itself a time-dependent collection. <p/> Note that each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rDKZQEKVnQdmACrINeAfsGw" class="cyc_term">EmptyCollection</a> is <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViA45wpEbGdrcN5Y29ycA" class="cyc_term">disjointWith</a> (q.v.) every collection -- including itself. <p/> Cf. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r_3mf2qedQdmNjeDW39lDKA" class="cyc_term">NonEmptyCollection</a>. EmptyCollection empty collection A collection of collections and a specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv1ZxY5wpEbGdrcN5Y29ycA" class="cyc_term">EmptySetOrCollection</a> (q.v.). A collection is an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rDKZQEKVnQdmACrINeAfsGw" class="cyc_term">EmptyCollection</a> if and only if it has no instances. <p/> Some collections are by their very nature necessarily empty; e.g. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv7LKYpwpEbGdrcN5Y29ycA" class="cyc_term">Nothing</a> (q.v.). Conversely, some collections are empty in some contexts and non-empty in others; e.g. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvhn_I5wpEbGdrcN5Y29ycA" class="cyc_term">Unicorn</a> might be empty in the context of the actual world but non-empty in certain mythological contexts. Similarly, a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwIE23ZwpEbGdrcN5Y29ycA" class="cyc_term">TimeDependentCollection</a> might be empty at certain times and non-empty at certain other times; e.g. the collection of female US presidents is currently empty but will hopefully become non-empty some time in the near future. This last example demonstrates that <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rDKZQEKVnQdmACrINeAfsGw" class="cyc_term">EmptyCollection</a> is itself a time-dependent collection. <p/> Note that each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rDKZQEKVnQdmACrINeAfsGw" class="cyc_term">EmptyCollection</a> is <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViA45wpEbGdrcN5Y29ycA" class="cyc_term">disjointWith</a> (q.v.) every collection -- including itself. <p/> Cf. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r_3mf2qedQdmNjeDW39lDKA" class="cyc_term">NonEmptyCollection</a>. EmptyCollection A collection of collections. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwIE23ZwpEbGdrcN5Y29ycA" class="cyc_term">TimeDependentCollection</a> is a collection whose membership changes over time. For example, (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwPzX35wpEbGdrcN5Y29ycA" class="cyc_term">LiquidFn</a> <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjAHZwpEbGdrcN5Y29ycA" class="cyc_term">Water</a>) is a time dependent collection. A given portion of water might be an instance of (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwPzX35wpEbGdrcN5Y29ycA" class="cyc_term">LiquidFn</a> <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjAHZwpEbGdrcN5Y29ycA" class="cyc_term">Water</a>) in the summer, and an instance of the disjoint collection (<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwPzX0JwpEbGdrcN5Y29ycA" class="cyc_term">SolidFn</a> <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjAHZwpEbGdrcN5Y29ycA" class="cyc_term">Water</a>) in the winter. In contrast, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVieEpwpEbGdrcN5Y29ycA" class="cyc_term">Integer</a> is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvzndCZwpEbGdrcN5Y29ycA" class="cyc_term">TimeIndependentCollection</a> (q.v.) because the collection of integers does not change its membership over time. time dependent collection TimeDependentCollection type of thing Collection A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjl_ZwpEbGdrcN5Y29ycA" class="cyc_term">SetOrCollection</a> (q.v.). This is the collection of all collections of things. Each <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViAzJwpEbGdrcN5Y29ycA" class="cyc_term">Collection</a> is a kind or type of thing whose instances share a certain property, attribute, or feature. For example, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVkFc5wpEbGdrcN5Y29ycA" class="cyc_term">Cat</a> is the collection of all and only cats, and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwOckfJwpEbGdrcN5Y29ycA" class="cyc_term">BinaryFunction</a> is the collection of all and only functions taking two arguments. <p/> The notion of collection is fundamental to the Cyc ontology, and is thus difficult to define in a precise and substantive way. But it is instructive to compare it to the mathematical notion of a set (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvl2en5wpEbGdrcN5Y29ycA" class="cyc_term">Set_Mathematical</a>). Like a set, a collection is an <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rpJ-nSEkJQdeC8NLkYPDBBw" class="cyc_term">AbstractThing</a> (i.e. aspatial and atemporal) that is not an <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjaApwpEbGdrcN5Y29ycA" class="cyc_term">Individual</a> (cf.), but instead has elements (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwGWaK5wpEbGdrcN5Y29ycA" class="cyc_term">elementOf</a>). Unlike a set, however, the elements or &quot;instances&quot; (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViBBJwpEbGdrcN5Y29ycA" class="cyc_term">isa</a>) of a given collection can vary from context to context, and it is possible for distinct collections to have exactly the same elements (i.e. to have the same <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwN2YGZwpEbGdrcN5Y29ycA" class="cyc_term">extent</a>) with respect to a given context. For example, the (non-reified) collections &quot;Chordate&quot; and &quot;Renate&quot; are co-extensional in the context of the present-day actual world, but have differring extents with respect to hypothetical contexts in which there exist creatures having hearts but not kidneys. This difference is sometimes summarized by saying that sets are &quot;extensional&quot; things and collections are &quot;intensional&quot; things. <p/> Many, though by no means all, of the collections reified in the Cyc ontology correspond to natural kinds or classes. It is particulary useful to reify collections that are difficult to define precisely, but about which there are many common-sense rules and other things to state. For example, it would not be worthwile to introduce a constant 'WhiteCat', both because it's easy to define the collection of white cats in terms of more general, already-reified notions (e.g. '(<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwEcGC5wpEbGdrcN5Y29ycA" class="cyc_term">CollectionIntersection2Fn</a> <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVkFc5wpEbGdrcN5Y29ycA" class="cyc_term">Cat</a> <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rBjWwGHS-EdaAAACgyZzFrg" class="cyc_term">WhiteColor</a>)'), and because there's not much to say about that particular collection. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rsX6vHnS6EdaAAACgyZzFrg" class="cyc_term">WhiteCollarWorker</a>, on the other hand, is a good collection to have reified, as it is hard to define precisely, yet is a collection about which there are many things to say. <p/> Some of the many reified specializations of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViAzJwpEbGdrcN5Y29ycA" class="cyc_term">Collection</a> are <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rHIBS0h_TEdaAAABQ2rksLw" class="cyc_term">FirstOrderCollection</a>, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwIE23ZwpEbGdrcN5Y29ycA" class="cyc_term">TimeDependentCollection</a>, and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVirnZwpEbGdrcN5Y29ycA" class="cyc_term">ObjectType</a>. VariedOrderCollection A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvtppU5wpEbGdrcN5Y29ycA" class="cyc_term">CollectionType</a> and the collection of all and only those <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViAzJwpEbGdrcN5Y29ycA" class="cyc_term">Collection</a>s some of whose instances (or instances of instances, or instances of instances of instances, etc.) are of different &quot;orders&quot;, where order is understood as follows. Let <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjaApwpEbGdrcN5Y29ycA" class="cyc_term">Individual</a>s be &quot;zeroth-order&quot; things, collections of (only) <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjaApwpEbGdrcN5Y29ycA" class="cyc_term">Individual</a>s &quot;first-order&quot;, ..., and collections of (only) Nth-order things &quot;(N+1)th-order&quot;. A more precise, recursive definition, then, is: a collection COL is an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rNs-F0CChEdaAAABQ2rksLw" class="cyc_term">VariedOrderCollection</a> if and only if COL has instances INST1 and INST2 such that either (i) INST1 and INST2 are of two different fixed orders N1 and N2, (ii) INST1 is of the fixed order N1 and INST2 is a varied-order collection, or (iii) INST1 and INST2 are both varied-order collections. <p/> For example, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rpJ-nSEkJQdeC8NLkYPDBBw" class="cyc_term">AbstractThing</a> is a varied-order collection since it contains both (zeroth-order) abstract individuals and (higher-order) collections. Other instances of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rNs-F0CChEdaAAABQ2rksLw" class="cyc_term">VariedOrderCollection</a> include <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjjo5wpEbGdrcN5Y29ycA" class="cyc_term">Intangible</a>, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViAzJwpEbGdrcN5Y29ycA" class="cyc_term">Collection</a>, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvtppU5wpEbGdrcN5Y29ycA" class="cyc_term">CollectionType</a>, and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViA9JwpEbGdrcN5Y29ycA" class="cyc_term">Thing</a>. Note that (by clauses ii and iii) any generalization of a varied-order collection is varied-order; and (by clause iii) any (non-empty) specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rNs-F0CChEdaAAABQ2rksLw" class="cyc_term">VariedOrderCollection</a> is varied-order. <p/> Note that <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rNooX_CChEdaAAABQ2rksLw" class="cyc_term">FixedOrderCollection</a> (q.v.) and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rNs-F0CChEdaAAABQ2rksLw" class="cyc_term">VariedOrderCollection</a> do _not_ constitute a partition of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViAzJwpEbGdrcN5Y29ycA" class="cyc_term">Collection</a>: since the notion of order described above is not applicable to sets, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvl2en5wpEbGdrcN5Y29ycA" class="cyc_term">Set_Mathematical</a> (e.g.) and its specializations are neither fixed-order nor varied-order collections. variable-order Cyc collection