1. Cyc Jaehui Park Summarized by Jaehui Park, IDS Lab., Seoul National University Presented by Jaehui Park, IDS Lab., Seoul National University

2. Copyright  2008 by CEBT CycL  Declarative language Syntax derives from – first-order predicate calculus – Lisp CycL expressions – consist of Terms Constants, non-atomic terms, variables It goes far beyond first order logic – In order to express common sense 2

3. Copyright  2008 by CEBT Constants  The concept names in Cyc Vocabulary words in Cyc knowledge base  Starting with “#$”  Individuals #$ BillJ, #$MapleTree #$France  Collections #$Tree-ThePlant (instance of the collection)  Truth Functions Being applied to one or more concepts and return true or false Connectives – #$and,#$or, #$not, #$implies Quantifiers – #$forAll, #$thereExists  Functions Producing new terms from given ones – #$FruitFn (a type of plants -> return the collection of its fruits) 3

4. Copyright  2008 by CEBT Connectives & Quantification  Logical Connectives #$not, #$and, #$or #$implies – Returns true iff it is not the case that its first argument is true and its second argument is false E.g. – (#$implies (#$owns #$Fred #$Bike001) (#$colorOfObject #$Bike001 #$RedColor))  Quantification #$forAll, #$thereExists, #$thereExistExactly, #$thereExistAtLeast, #$thereExistAtMost E.g. – (#$implies (#$isa ?A #$Animal) (#$thereExists ?M (#$mother ?A ?M))) 4

5. Copyright  2008 by CEBT Variables  Constants whose identities are not specified  Starting with “?”  E.g. (?FOO)  E.g. (#$colorOfObject ?CAR ?COLOR)  CycFormula A formula is an expression in a formal language that makes some declarative statement about the world. – Well-formed formulas are called CycFormular – E.g. (#$likesAsFriend #$DougLenat #$KeithGoolsbey) 5

6. Copyright  2008 by CEBT Specialization & Generalization  Predicates #$isa – Specialization Describing the one item is an instance of some collection #$genls – Generalization Describing the one collection is a subcollection of another one  Examples (#$isa #$GeorgeBush #$UnitedStatesPresident) \; – George Bush belongs to the collection of U.S. presidents (#$genls #$Tree-ThePlant #$Plant) \; – All trees are plants (#$capitalCity #$France #$Paris) \; – Paris is the capital of France 6

7. Copyright  2008 by CEBT Rules  Sentence containing variables  Starting with “?”  Example (#$implies (#$and (#$isa ?OBJ ?SUBSET) (#$genls ?SUBSET ?SUPERSET)) (#$isa ?OBJ ?SUPERSET)) – If OBJ is an instance of the collection SUBSET and SUBSET is a subcollection of SUPERSET, then OBJ is an instance of the collection SUPERSET. 7

8. Copyright  2008 by CEBT Assertions  CYC knowledge base A large number of assertions – A formula CycFormlas – A microtheory Cyc constant denoting assertions which are grouped together because they share a set of assumptions #$Microtheroy – A truth value :#$isa, #$genls – A direction Hierarchy of “when it gets used” – A support Consists of one or more justifications which form the support the presence of the assertion in the KB. 8