Event Linking With Meaning: Ontological Hypertext and the Semantic Web Hugh Davis Learning Societies Lab ECS The University of Southampton, UK All Notes on

Event Typed links Early Hypertext systems typically allowed links to be “typed”. The advantage is that the links has some “semantics” (= meaning) When we see a link we have some understanding of what we will get by following it. And we might be able to deduce information If the semantics are well defined then maybe a machine can deduce information too. 2

Event3 What is Ontological Hypertext? Ontological Hypertext = Hypertext + Ontologies Ontology is the study of things that exist –Began as branch of philosophy –Popular in the field of knowledge management –Formal model that allows reasoning over concepts and objects that appear in the real world –An Ontology is a taxonomy (the classes within a domain and the relationship between them) and the inference rules

Event4 What is Ontological Hypertext? Ontological Hypertext = Hypertext + Ontologies As we know, hypertext is the study of what can be said using computer media, databases and links –Computer-mediated extensions to familiar textual communication

Event5 What is Ontological Hypertext? Ontological Hypertext = Hypertext + Ontologies Things that exist have complex relationships with each other –So complex structures are required for expressing and exploring these relationships –Ontologies formalise these complex structures Ontological Hypertext is the kind of hypertext whose structure and links are derived from the relationships between objects in the real world –Hypertext with an underlying ontological model

Event6 Ontology Construction We know various ways to construct a hypertext, but how to construct an ontology for a domain? –Get together a wide range of experts (domain experts, end-users, computer specialists) to ensure all aspects, issues and perspectives of the domain are covered –Iteratively refine and evaluate ontology –Document the construction process, including all assumptions made, in order to aid ongoing maintenance Domains are not always static, need to incorporate new discoveries, ideas etc.

Event7 Ontology Formalisation Once consensus reached, ontology must be formalised –Make the model machine-processable –Variety of different formalisation languages RDFS DAML -> OIL -> DAML+OIL -> OWL are more expressive, –Extended type systems –Constraint mechanisms and inference rules –

Event8 Authoring Ontological Hypertext Use formalised ontology as basis for authoring nodes and links in hypertext system –E.g. select type of node to create –Offer appropriate links to other nodes Example GUIs coming up!

Event9 FREMA

Event10 FREMA (2)

Event11 What about the Semantic Web? Complimentary approaches –Instantiating ontologies as hypertext nodes and links

Event12 The Semantic Web Tim Berners-Lee (1999 WWW keynote) “ I have a dream for the Web [in which computers] become capable of analyzing all the data on the Web – the content, links, and transactions between people and computers. A ‘Semantic Web’, which should make this possible, has yet to emerge, but when it does, the day- to-day mechanisms of trade, bureaucracy and our daily lives will be handled by machines talking to machines. The ‘intelligent agents’ people have touted for ages will finally materialize. “intelligent agents

Event13 What’s Wrong with Google? Find me some teaching materials to help 12 year olds understand basic programming concepts How many days was it above 14 deg C in Western Australia in 2005? Did anyone from the TOIA project also work on FREMA? I want to go somewhere to do some windsurfing this Christmas. What’s the cheapest available way of doing this?

Event14 Principle Formats XML - for the structured data + RDF - for the relationships + OWL – to represent the ontology and inference rules

Event15 Case Study CS-Aktive Space A tool for exploring activity within the UK Computer Science Research domain –across multiple dimensions –for multiple stakeholders (from funding agencies to individual researchers.) Where would you get this data from? Would it be machine processable?

Event16 CS-Aktive Space Data Sources This requires harvesting data from heterogeneous sources e.g. –Funding councils’ databases –University sites –Bibliographical Sources (inc Abstracts and ePrints) –Geographical gazetteers –UK Research Assessment Exercise submissions –Direct submissions by Partners And fitting the information located to the domain ontology

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Event18 CS-Aktive Space Research Issues how to best sustain an acquisition and harvesting activity? how best to model the harvested content? how to cope with large numbers of duplicate items that need to be recognized as referring to the same objects? the degree to which inferential services can cope as more content becomes available;? how we present the content so that inherent patterns and trends can be directly discerned? how trustworthy is the provenance and accuracy of the content? how all this information is to be maintained and sustained as a social and community exercise?

Event Linked Data The Web of Data Tim Berners-Lee outlined four principles: –Use URIs to identify things. –Use HTTP URIs so that these things can be referred to and looked up ("dereference") by people and user agents. –Provide useful information (i.e., a structured description — metadata) about the thing when its URI is dereferenced. –Include links to other, related URIs in the exposed data to improve discovery of other related information on the Web. e.G DBPedia 19

Event20 Some Issues for the Semantic Web It hasn’t really happened yet – but maybe linked data is taking off (2009) Link and Data. We really need to be able to get semantic data from textual data -> RDFa and GRDDL. The Semantic Gap – whose ontology? If it did work would we be happy – or in control of the data – c.f. the Facebook API