BBY 464 Semantic Information Management Spring 2016 Semantic

BBY 464 Semantic Information Management (Spring 2016) Semantic Web Yaşar Tonta & Orçun Madran [yasartonta, orcunmadran]@gmail. com Hacettepe University Department of Information Management

Knowledge representation • XML: lets everyone create their own tags • RDF: expresses meaning using triples (subject, verb, and object) – “Orçun teaches BBY 464. ” – Uses URIs to describe them: – Subject: www. madran. net/orcun_madran – Object: http: //www. acikders. net/course/view. php? id=114 – Verbs (“teach”) are identified by URIs as well

RDF example with URIs and RDF/XML

Ontologies http: //yunus. hacettepe. edu. tr/~tonta/ RDFS: Resource Description Framework Schema OWL: Web Ontology Language

Shallow ontologies

Deep ontologies

Agents • “bots” (to find tickets, hotels, etc. ) • “shared meaning”

Expressing Meaning • Date – February 16, 2016 – 16 February 2016 – 16/02/2016 – 02/16/2016 – What about “ 03/03/2016” –… • Shoe sizes

Data quality and interpretation • Semantic differences • Interpretation problems (metric system, “year” - last 12 months, calendar year, financial year…) Source: Madnick & Zhu, 2006, p. 462, 466

Meaning • Metaphors • Thought cannot exist without metaphors. Susan Sontag “Tartışma Savaştır İddialarınız savunulamaz. Argümanımdaki her zayıf fikre saldırdı. Eleştirileri doğrudan hedefi buldu. Argümanını yerle bir ettim. Onunla asla bir tartışmada galip gelemedim. Kabul etmiyor musun? O zaman, ateş! Bu stratejiyi kullanırsan o seni bitirecek. Argümanlarımın hepsini tahrip etti. ” 28. -G. Lakoff ve M. Johnson, Metaforlar: Hayat, Anlam ve Dil. İstanbul: İthaki. S. • Disambiguity – “Visiting relatives can be a nuisance”

Seks metaforları (ABD)

Logic • Rules and inference – “This sentence is false” • RIF: Rule Interchange Format

Proof Validation

Semantic Web – Layered Architecture