CS621 : Artificial Intelligence Pushpak Bhattacharyya CSE Dept., IIT Bombay Lecture 12 RDF, OWL, Minimax

RDF recap

Fundamental Triple E.g., And so on

Namespace Give meaning to a name Specifically, bind a name with an URI (uniform resource identifier in the web) Pushpak {person} Pushpak {movie}

Draw the names from the namespace I just got a new pet dog.

RDF: Resource Description Format Each RDF statement has three parts: a subject, a predicate and an object Makes statements about resources on the web, uniquely identified by URIs

Example (from W3C specification of RDF) In natural Language has a creator whose value is John Smith has a creation-date whose value is August 16, has a language whose value is English

Subject-Predicate-Object based scheme the subject is the URL the predicate is the word "creator" the object is the phrase "John Smith"

More concretely through URIs a subject a predicate and an object

In graphical form

With all other information

In triple notation Subject Predicate "August 16, 1999". Object "en".

Ontology

Building blocks Concepts Relationships instances

Taxonomic organization of knowledge

Simple Inference

Fundamental relationships Hypernymy Subclass (man mammal Membership (Ram ε man) Meronymy (part whole) (hand part-of body)

Languages for representing ontology RDF/RDFS DAML+OIL OWL

Systems for representing ontology Wordnet CYC UMLS

From National Library of Medicine Unified Medical Language System (UMLS®) to facilitate the development of computer systems that behave as if they "understand" the meaning of the language of biomedicine and health UMLS Knowledge Sources (databases) and associated software tools (programs) Systems that create, process, retrieve, integrate, and/or aggregate biomedical and health data and information patient records, scientific literature, guidelines, public health data

UMLS semantic n/w Major groupings of semantic types include organisms, anatomical structures, biologic function, chemicals, events, physical objects, and concepts or ideas. Is-a hierarchy Non-hierarchical relations:`physically related to,' `spatially related to,' `temporally related to,' `functionally related to,' and `conceptually related to.'

How is ontology used In IR: query expansion In expert systems: for generalization

Layering XML RDF Schemas and Ontologies User given tags and arbitrary structure Meaning Sharable and reusable information

Spectrum of ontologies Amount of meaning and formality increases left to right terms Data dictionaris thesauri XML DTD DB schema XML Schema Formal Taxonomy Frame Description Logic General Logic

Web ontology language OWL lite OWL DL OWL full

OWL (Web Ontology Language)

Structure of OWL document Name space Name Space name owl OWL header: version information, ontology comments, import statements, title, creator etc. Owl:imports used to import other ontologies

OWL classes OWL: Thing OWL: Nothing Classes named using URLs Anonymous classes possible

Class description as property restriction Value restrictions OWL: AllValuesFrom OWL: SomeValuesFrom OWL: hasValue Cardinality restrictions OWL: minCardinality OWL: maxCardinality OWL: cardinality

Value Restrictions 1) 2) 3) 2) 1) 2) 3) 1) 2) 3) Elective is an individual in the ontology

Cardinality Restrictions 1) 6 2) 1 3) 1

Complex classes Owl: Union Of Owl: IntersectionOf Owl: ComplementOf

Examples of Complex Classes: unionOf

Examples of Complex Classes: intersectionOf

Examples of Complex Classes: complementOf 1. 2.

Class Axioms: subclassOf

Class Axioms: equivalentClass

Class Axioms: disjointWith

Other operations

Minimax with alpha-beta cut

An example search tree S A B C D E F G HI J evaluations

Minimax with alpha-beta pruning (DFS)- step S A D E F Backup=7

Minimax with alpha-beta pruning (DFS)- step S A B D E F G H 5 Can only decrease Need not be generated 7

Minimax with alpha-beta pruning (DFS)- step S A B C D E F G H I J 7 Need not be generated

An example in predicate calculus

A “department” environment 1. Dr. X is the HoD of CSE 2. Y and Z work in CSE 3. Dr. P is the HoD of ME 4. Q and R work in ME 5. Y is married to Q 6. By Institute policy staffs of the same department cannot marry 7. All married staff of CSE are insured by LIC 8. HoD is the boss of all staff in the department

Questions on “department” Who works on CSE? Is there a married person in ME? Is there somebody insured by LIC?