Old Wine in New Bottles? The Semantic Web COMP34512 Sebastian - - PowerPoint PPT Presentation

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Old Wine in New Bottles? The Semantic Web COMP34512 Sebastian - - PowerPoint PPT Presentation

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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

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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

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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

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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

Tuesday, 6 May 2014

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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

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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

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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

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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

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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.

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  • 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?

The Hypertext Analogy

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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

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Process: Decentralization?

  • Not very directive!
  • Do these things even exist in KR?
  • What does it take to remove them?
  • What are the problems of centralization?

“We remove the centralized concepts of absolute truth, total knowledge, and total provability, and see what we can do with limited knowledge.”

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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

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1) Uploading a KR to the Web

  • Still a popular mechanism!

– The Web is effective at sharing files – And more!

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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!

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Effects on Research: Depth

  • Publishing systematically yields benefits

– NCIt published monthly for 10 years – Can study the evolution of ontologies

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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)

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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

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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

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3) Publishing a Web Based KR App

http://www.isi.edu/isd/LOOM/PowerLoom/documentation/ontosaurus-screenshot.gif 20

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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

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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

A (Private) Semantic Web!

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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

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Do we still need decentralization?

  • In 1993, the Web >>> any 1 org’s capacity
  • Today?

–Google, Amazon, Facebook, etc. –Can handle both the data and the people “We remove the centralized concepts of absolute truth, total knowledge, and total provability, and see what we can do with limited knowledge.”

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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

Tuesday, 6 May 2014

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URIs: Distinctive? (Uniform Resource Identifier)

Tuesday, 6 May 2014

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Global Communication

In order to communicate internally, a community agrees…on a set of terms and their meanings. One goal of the Web…has been to build a global community in which any party can share information with any other party.

! To achieve this goal, the Web makes use of a single global identification system: the URI. URIs are a cornerstone of Web architecture, providing identification that is common across the Web. The global scope of URIs promotes large-scale "network effects": the value of an identifier increases the more it is used consistently…

http://www.w3.org/TR/webarch/#identification

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The Magic of Linking?

  • In HTML

– URLs/URIs/IRIs are key – URL design within a Website – URL design between sites

  • What can they do for us?

– Linked data? – Web ontologies? – URIs are everywhere

  • But what are they doing?

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Linked Data “Principles”

  • Linked Data is the new cool fad!
  • 1. Use URIs as names for things
  • 2. Use HTTP URIs so that people can look up those names.
  • 3. When someone looks up a URI, provide useful information,

using the standards (RDF*, SPARQL)

  • 4. Include links to other URIs. so that they can discover more

things.

http://www.w3.org/DesignIssues/LinkedData.html

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Linked Data “Principles”

  • Linked Data is the new cool fad!
  • 1. Use URIs as names for things
  • 2. Use HTTP URIs so that people can look up those names.
  • 3. When someone looks up a URI, provide useful information,

using the standards (RDF*, SPARQL)

  • 4. Include links to other URIs. so that they can discover more

things.

  • Still not very directive!

– Some direction

  • More than said here: E.g., “reuse URIs”

– Entity and attribute reconciliation?!

– “Providing useful information” is tricky

  • Esp. for programs!
  • Meaning of terms....ontologies?!

– (In the broadest sense of the term)

http://www.w3.org/DesignIssues/LinkedData.html

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Where are we?

  • What’s the linking?

– Ask yourself what sorts of links there are – Ask yourself what do the links support

  • And who (or what) exploits them

– What makes a linked datum?

  • And what value add over an unlinked one?
  • What’s the useful information?

– What sort of information could there be? – What makes it useful?

  • For what task?
  • Many open questions

– Which may be closing negatively!

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