Old Wine in New Bottles? The Semantic Web COMP34512 Sebastian Brandt brandt@cs.manchester.ac.uk (Slides by Bijan Parsia, bparsia@cs.man.ac.uk) Tuesday, 6 May 2014
From Web to Semantic Web The Semantic Web is not a separate Web but an extension of the current one, in which information is given well-defined meaning , better enabling computers and people to work in cooperation. “The Semantic Web” by Tim Berners-Lee, James Hendler, and Ora Lassila, Scientific American, 2001 2 Tuesday, 6 May 2014
The Basic Web • We have –URLs/URIs/IRIs –HTTP –HTML (and XML based formats, JSON, etc.) • People interact with the web – Via hypermedia (the web browser) • Web sites wrap databases, mail, chat, message boards, stores, management systems, etc. etc. etc. –Programmatically • Via “raw” HTTP • Via Web Services –Other interfaces • Esp. in mobile 4 Tuesday, 6 May 2014
Programs vs. People • Access to the information on the (HTML) Web • Primarily designed for people • People read web pages • People click on links • People read more pages • What’s on those pages? • “Information”, data, knowledge • How do we • write programs • that manipulate that info? • 2 choices • Scrape • Structure 5 Tuesday, 6 May 2014
Interlude: Web Applications • The HTML web has not stood still! • Web 2.0/AJAX • XMLHttpRequest – JSON! • HTML 5 • Applications, not documents or data! • Mobile Apps • Not even HTML! • Attenuated linking • Lots of data floating around • Public and private • Lots of data silos • But lots of APIs/endpoints as well 6 Tuesday, 6 May 2014
The KR Vision Knowledge representation is a field which is currently seems to have the reputation of being initially interesting, but which did not seem to shake the world to the extent that some of its proponents hoped. It made sense but was of limited use on a small scale, but never made it to the large scale. This is exactly the state which the hypertext field was in before the Web. Each field had made certain centralist assumptions -- if not in the philosophy, then in the implementations, which prevented them from spreading globally. But each field was based on fundamentally sound ideas about the representation of knowledge. The Semantic Web is what we will get if we perform the same globalization process to Knowledge Representation that the Web initially did to Hypertext. We remove the centralized concepts of absolute truth, total knowledge, and total provability, and see what we can do with limited knowledge. http://www.w3.org/DesignIssues/RDFnot.html 7 Tuesday, 6 May 2014
Knowledge Representation • “Knowledge” – Comes in different forms • Knowing that vs. knowing how (or “know-how) • “Propositional” vs. “procedural” • Representation – Anything with “aboutness” – Different representations have different properties • We want “computable” represenations • Knowledge + Representation? – (“KR” or sometimes “KRep) – Computable representations of human propositional knowledge • A working definition! • For our purposes, generally based on a logic 8 Tuesday, 6 May 2014
The Sorry-State-of-KR Argument • Knowledge representation is a field which – currently seems to have the reputation of being initially interesting, but – did not seem to shake the world to the extent that some of its proponents hoped. • It made sense – but was of limited use on a small scale, – but never made it to the large scale. • This is exactly the state which the hypertext field was in before the Web. 9 Tuesday, 6 May 2014
The Hypertext Analogy • Each field [e.g., hypertext] had made certain centralist assumptions -- –if not in the philosophy, then in the implementations, –which prevented them from spreading globally. –But each field was based on fundamentally sound ideas about the representation of knowledge. • The Semantic Web is what we will get –if we perform the same globalization process to Knowledge Representation –that the Web initially did to Hypertext. –(Call this the Argumentum ad WebSuccessam) • What is this globalization process? • What is the value we hope for? 10 Tuesday, 6 May 2014
The Value • Having A Web Sized KR –All knowledge captured in a computable form –Who knows? • Human level or greater AI? • Better cognitive prosthetics –Computing at that scale is a...challenge • Having A Web Of KRs –Ad hoc integration becomes easier –Less code and effort on understanding data • and more on using it • E.g., Semantic Search 11 Tuesday, 6 May 2014
Process: Decentralization? “We remove the centralized concepts of absolute truth, total knowledge, and total provability, and see what we can do with limited knowledge.” • Not very directive! • Do these things even exist in KR? • What does it take to remove them? • What are the problems of centralization? 12 Tuesday, 6 May 2014
How to Combine Web & KR 1. Uploading a KR to the Web 2. Mining the Web to Generate a KR 3. Publishing a Web Based KR App 4. Something distinctive 13 Tuesday, 6 May 2014
1) Uploading a KR to the Web • Still a popular mechanism! – The Web is effective at sharing files – And more! 14 Tuesday, 6 May 2014
Profound effects on KR Research • 2002 ≈ 200 ontologies on the Web • 2006 ≈ 1000 ontologies on the Web • 2011 ≈ 30,000 ontologies on the Web • Size and complexity of ontologies growing • Tools can handle them! 15 Tuesday, 6 May 2014
Effects on Research: Depth • Publishing systematically yields benefits – NCIt published monthly for 10 years – Can study the evolution of ontologies 16 Tuesday, 6 May 2014
Effects on Practice? • Harder to say – Reuse and linking not esp. high • Designing for reuse is hard • Reusing is hard • Reinvention is the norm • “Standards” make progress on reuse – But usually high level and pushed hard (e.g., BFO) – Web based editing still in infancy • Most work is done with offline tools • See software engineering • Standard Web Benefits – Examples – Feedback – Standardization of formalisms – Indirect (tools get better) 17 Tuesday, 6 May 2014
2) Mining the Web • The Web is an information resource – let’s use it • Use the content – DBpedia comes to mind • Use the people! – E.g. ConceptNet 2 18 Tuesday, 6 May 2014
Using People • Direct crowd sourcing – Let The People curate • Indirect crowd sourcing – Feedback and use – Map data! • Excellent for concrete facts – Unproven for more complex things 19 Tuesday, 6 May 2014
3) Publishing a Web Based KR App http://www.isi.edu/isd/LOOM/PowerLoom/documentation/ontosaurus-screenshot.gif 20 Tuesday, 6 May 2014
What is Wolfram Alpha? Wolfram|Alpha's long-term goal is to make all systematic knowledge immediately computable and accessible to everyone. We aim to collect and curate all objective data; implement every known model, method, and algorithm; and make it possible to compute whatever can be computed about anything. http://www.wolframalpha.com/about.html 21 Tuesday, 6 May 2014
What is Wolfram Alpha? Wolfram|Alpha's long-term goal is to make all systematic knowledge immediately computable and accessible to everyone. We aim to collect and curate all objective data; implement every known model, method, and algorithm; and make it possible to compute whatever can be computed about anything. A (Private) Semantic Web! http://www.wolframalpha.com/about.html 22 Tuesday, 6 May 2014
Interlude: Other Examples • Wolfram Alphaesqe – Evi/TrueKnowledge • Lighter understanding, narrower scope – Garlik • Deeper understanding, narrower scope – Watson • Even lighter understanding, even greater scale – Semantic Search in Google (Knowledge Graph) • 500 million objects • 3.5 billion facts • All fairly centralized! – Although they pull a lot from other sources – Share results but not data 23 Tuesday, 6 May 2014
Do we still need decentralization? “We remove the centralized concepts of absolute truth, total knowledge, and total provability, and see what we can do with limited knowledge.” • In 1993, the Web >>> any 1 org’s capacity • Today? –Google, Amazon, Facebook, etc. –Can handle both the data and the people 24 Tuesday, 6 May 2014
4) Something Distinctive • 1-3 are not fundamentally distinctive –Not a new web (really) –Not a new kind of KR • What would be a Webesque KR? –BTW: I’ve no idea •(OK, I’ve some ideas...) –Do we need such a thing? •Web distinctiveness might be overstated •Technology may have caught up –Google (or Facebook) could run the Web 25 Tuesday, 6 May 2014
URIs: Distinctive? (Uniform Resource Identifier) Tuesday, 6 May 2014
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