of 33 lecture 1: introduction

of 33 the semantic web vision today’s web (1) web content – for human consumption (no structural information) people search for information, keep in touch with other people, make purchases, look for entertainment … minimal support by software tools ece 720, winter'122

of 33 the semantic web vision today’s web (2) keyword-based search engines … with some problems:  high recall & low precision – too many documents retrieved  low/no recall – no relevant documents found  results sensitive to vocabulary – similar words not considered  results are single web pages – “distributed” information not retrieved  human needed for interpretation, no other software tools use the result ece 720, winter'123

of 33 the semantic web vision today’s web (3) a problem with semantics … so … a need for different representation of information, and intelligence that takes advantage of that ece 720, winter'124

of 33 the semantic web vision … the future (1) knowledge management  key activity of large businesses (knowledge seen as intellectual asset)  information is in a weakly structured form  problems with: sharing, extracting, marinating, viewing Semantic Web -> knowledge organized, tools for knowledge maintenance, query answering tools ece 720, winter'125

of 33 the semantic web vision … the future (2) business-to-customer electronic commerce  browsing on-line shops, selecting the best alternative/offer -> time and effort consuming activity  decisions making based on limited/partial information Semantic Web -> software “shopping” agents able to interpret the product information and the terms of service, and conduct negotiations ece 720, winter'126

of 33 the semantic web vision … the future (3) business-to-business electronic commerce  data exchange using the Electronic Data Interchange (EDI) approach (complex, isolated)  lack of standards Semantic Web -> differences in terminology resolved (abstract domain models), automatic translation of services, auctioning, negotiations, and drafting of contracts ece 720, winter'127

of 33 the semantic web vision … the future (4) wikis  collections of pages that allow users to add content (collaborative knowledge creation) Semantic Web -> usage of semantic technologies (enriching structured text and untyped hyperlinks with semantic annotation referring to an underlying model of the captured knowledge) ece 720, winter'128

of 33 the semantic web vision … the future (5) personal agents: a future scenario Michael has some neck pain, he asked his Semantic Web agent to arrange for him physical therapy sessions which were suggested by Michael’s physician … ece 720, winter'129

of 33 semantic web technologies metadata (1) HTML is the predominant language used for writing web pages humans have no problem reading it machines are not able to distinguish different people, things, follow links to find out more about topics – simple they have no clue what a given text is about ece 720, winter'1210

of 33 semantic web technologies metadata (2) … … ece 720, winter'1211

of 33 semantic web technologies metadata (3) HTML is replaced by a language that carries information about a content metadata – data about data, capture part of the meaning of data (tags that are “defined” in a systematic way) ece 720, winter'1212

of 33 semantic web technologies ontology (1) study of nature of existence, how to describe things that actually exist world is made up of specific objects that can be grouped into abstract classes based on shared properties it describes a domain of interest ece 720, winter'1213

of 33 semantic web technologies ontology (2) consists of a finite list of terms and the relationships between them terms denote concepts (classes of objects) of the domain relationships include hierarchies of classes + properties of objects, value restrictions, logical relationships between objects ece 720, winter'1214

of 33 semantic web technologies ontology (3) provide “a shared understanding of a domain” overcome differences in terminology ece 720, winter'1215

of 33 semantic web technologies ontology languages RDF – is a data model for objects and relations between them RDF Schema – a description language for describing properties and classes of RDF resources, provides a semantics for generalization hierarchies OWL – a rich language for describing properties and classes, and relations between them ece 720, winter'1216

of 33 semantic web versus AI logic (1) provides principles of reasoning provides well-understood formal semantics “unlocks” automated reasoners leads to uncovering ontological knowledge given implicitly ece 720, winter'1217

of 33 semantic web versus AI logic (2) used by intelligent agents for making decisions and selecting courses of action provides explanations for conclusions ece 720, winter'1218

of 33 semantic web versus AI logic (3) SWRL – semantic web rule language for constructing rules based on ontology classes and relationships ece 720, winter'1219

of 33 semantic web versus AI agents (1) software agents work autonomously and proactively ece 720, winter'1220

of 33 semantic web versus AI agents (2) tasks of personal software agent in SW:  receive tasks and preferences from users  seek information on the web, communicate with other agents  compare information from different sources, make choices  give answer to users ece 720, winter'1221

of 33 semantic web versus AI agents (3) metadata  identify and extract information ontology  web search, information interpretation  communication with other agents logic  information retrieval, conclusion derivation ece 720, winter'1222

of 33 a layered approach development of SW in steps each step building a layer on the top of another ece 720, winter'1223

of 33 a layered approach ece 720, winter'1224

of 33 a layered approach ece 720, winter'1225 alternative stack

of 33 a layered approach XML layer  syntactic basis RDF layer  basic data model for facts  RDF Schema simple ontology language ontology layer  more expressive languages - OWL ece 720, winter'1226

of 33 a layered approach logic layer  enhance ontology, application specific knowledge proof layer  proof generation, validation trust layer  digital signature, rating agents … ece 720, winter'1227

of 33 the semantic web vision … the present (1) linked data a new paradigm built on one of the layers of SW – RDF core ece 720, winter'1228

of 33 the semantic web vision … the present (2) linked data each piece of information is linked to other pieces different types of links different sources of data ece 720, winter'1229

of 33 the semantic web vision … the present (3) linked data every piece of information presented as a triple: subject-property-object ece 720, winter'1230

of 33 the semantic web vision … the present (4) linked data a vast, interconnected web of triples (pieces of information) easy to query with SPARQL – a special query language for RDF ece 720, winter'1231

of 33 the semantic web vision … linked data linked data ece 720, winter'1232

of 33 future web … intelligent representation and processing of data ece 720, winter'1233