lom = words / rdf = grammar? nahum korda. “one standard for all: why we don't want it, why we...
TRANSCRIPT
LOM = Words / RDF = Grammar?
Nahum Korda
“One Standard for All: Why We Don't Want It, Why We Don't Need It”
o Paraphrase from a presentation by Stephen Downes (Researcher at National Research Council, Alberta, Canada)
o Presentation delivered at the Athabasca University's Edmonton office
o The original argument: RDF is better because it is not restricted vocabulary (like LOM)
Semantic Web and Learning Objects
o Could LOM be formulated (presented) in RDF?
o Cold LOM be integrated with the Semantic Web?
o How useful is Semantic Web for LOM?
Semantic Web
o What is Semantic Web?
o What is RDF and how is it related to XML?
o What are ontologies?
o Demonstration
World Wide Web
o Markup Languages (HTML primarily)
o Meta-information (tags)
o Links to other files
o Global hyperlinked environment
New Concept of Document
o Not a single file
o A set of related hyperlinked files
• Content in various formats
• Formatting information
• Scripts and runtime applications
New Concept of Document
Script to scroll news feeds
XML from news feeds database
Graphic files
XML from directory
XSL file with formatting information
Flash from banner
exchange database
New Concept of Document
o A single focal point for representing all the relevant information from a wide variety of information resources
o Different readability
• No reading order
• Information cannot be provided chronologically
• Information must be simultaneously available
Semantic Web
o Additional layers of information
• Lexical definitions
• Links to other relevant documents
• Links to relevant people
Semantic Web
o What is Semantic Web?
o What is RDF and how is it related to XML?
o What are ontologies?
o Demonstration
Semantic Web
o Generate these layers automatically
o Allow software agents to manipulate this information
Resource Description Framework
o Not just machine readable information
o Also machine understandable information
Resource Description Framework
<?xml version="1.0" ?><rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:s="http://description.org/schema/">
<rdf:Description about="http://www.w3.org/Home/Lassila" bagID="D_001"><s:Creator>Ora Lassila</s:Creator><s:Title>Ora's Home Page</s:Title>
</rdf:Description></rdf:RDF>
Resource Description Framework
o Subject
o Predicate
o Object
Resource Description Framework
Ora Lassila is the creator of the resource
http://www.w3.org/Home/Lassila.
Resource Description Framework
Subject (Resource) http://www.w3.org/Home/Lassila
Predicate (Property) Creator
Object (literal) "Ora Lassila"
Resource Description Framework
Semantic Web
o What is Semantic Web?
o What is RDF and how is it related to XML?
o What are ontologies?
o Demonstration
Ontology
o System of concepts and relations between them:
• Table [is piece of] furniture
• Arm [is part of] body
• Japan [is located in] East Asia
o A method for storing and representing knowledge
Ontology
Semantic Web
o Software applications can utilize meta-information for:
• Annotations
• Automatic summarization
• Hyperlinking
• Filtering
Notations for Logic
o Conceptual Graph Interchange Form (CGIF)
[Go: *x] [Person: 'John' *y] [City: 'Boston' *z] [Bus: *w] (Agnt ?x ?y) (Dest ?x ?z) (Inst ?x ?w)
o Knowledge Interchange Format (KIF)
(exists ((?x Go) (?y Person) (?z City) (?w Bus)) (and (Name ?y 'John) (Name ?z 'Boston) (Agnt ?x ?y) (Dest ?x ?z) (Inst ?x ?w)))
RDF and Ontologies
o DARPA Agent Markup Language (DAML)
o Ontology Interchange Language (OIL)
o An extension to XML and RDF
DAML+OIL
<rdfs:Class rdf:ID="BigFoot"> <rdfs:comment>
BigFoots (BigFeet?) are exactly those persons whose shosize is over12.</rdfs:comment> <daml:intersectionOf rdf:parseType="daml:collection">
<rdfs:Class rdf:about="#Person"/><daml:Restriction>
<daml:onProperty rdf:resource="#shoesize"/><daml:hasClass
rdf:resource="http://www.w3.org/TR/2001/NOTE- daml+oil-walkthru-20011218/daml+oil-ex-dt#over12"/>
</daml:Restriction></daml:intersectionOf>
</rdfs:Class>
Problems with Ontologies
o Development and maintenance of ontologies is extremely complex and resource consuming
o A useful ontology is domain specific and many various ontologies need to be developed in order to cover a variety of possible interests
o Ontologies suffer from problems related to the intrinsic complexity
Intrinsic Complexity
o Concepts in ontologies are often highly ambiguous
o Ontologies must often handle multi-lingual document corpora
o Criteria for defining interrelationships are typically highly inconsistent
Month in Calendar
Historical Event
Imaginary Naval Vessel
Ambiguity
o Weather in October is unstable.
o Red October was one of the most important historical events in the 20th Century.
o This was the first time that American military personnel came aboard Red October.
Multilingualism
Inconsistency
EllipseCircleis a subtype of
Mathematical Ontology
EllipseCircleis a subclass of
Object-Oriented Programming Language
Automated Idiomatic Representation
o Words are not mathematical variables
o Meaning is generated on the pragmatic (contextual) level – not semantic!
o The meaning of a word is its use in the language. (Ludwig Wittgenstein, Philosophical Investigations, 43)
Automated Idiomatic Representation
Semantic Web
o What is Semantic Web?
o What is RDF and how is it related to XML?
o What are ontologies?
o Demonstration
Loads of Buzz – Little to Show
o Dublin Core Metadata - DC 15 core metadata categories can be expressed in RDF in web pages
o MusicBrains metadata initiative - storing and exchanging metadata related to digital audio and video tracks
o ELSST thesaurus - EU thesaurus project drafted RDF format for ISO multilingual thesauri standard and the ELSST multi-lingual thesaurus of social science terms encoded in RDF
Loads of Buzz – Little to Show
o Annotea and Mozilla support RDF annotation servers that allow users to annotate web pages
o Open Directory Project (DMOZ) - a hand crafted web directory that uses RDF to store the details of web sites
Semantic Web and Learning Objects
o Could LOM be formulated (presented) in RDF?
o Cold LOM be integrated with the Semantic Web?
o How useful is Semantic Web for LOM?
How useful is Semantic Web for LOM?
o Discovery
• Search more efficiently
• Apply automation to information retrieval
o Interoperability
• Automate reusability
• Bridge multilingualism
Cold LOM be integrated with the SW?
o Restricted vocabulary necessary in order to make it interoperable
o Restricted vocabulary imposes severe limitations to expressibility
Restricted Vocabulary - Necessity
o [Go: *x] [Person: 'John' *y] [City: 'Boston' *z] [Bus: *w] (Agnt ?x ?y) (Dest ?x ?z) (Inst ?x ?w)
o [Go: *x] [Person: 'John' *y] [City: 'Boston' *z] [Bus: *w] (Actr ?x ?y) (Dest ?x ?z) (Inst ?x ?w)
o Agnt = Actr ?
o Agnt ⊂ Actr ?
o Agnt ⊃ Actr ?
o Agnt ⋂ Actr ?
Restricted Vocabulary - Limitation
DE PROFUNDIS
There is a stubble field on which a black rain falls. There is a tree which, brown, stands lonely here. There is a hissing wind which haunts deserted huts - how sad this evening. Past the village pond the gentle orphan still gathers scanty ears of corn. Golden and round her eyes are gazing in the dusk and her lap awaits the heavenly bridegroom. Returning home shepherds found the sweet body decayed in the bramble bush. A shade I am remote from somber hamlets. The silence of God I drank from the woodland well. On my forehead cold metal forms. Spiders look for my heart. There is a light that fails in my mouth. At night I found myself upon a heath, thick with garbage and the dust of stars. In the hazel copse crystal angels have sounded once more.
Georg Trakl (1887-1914)
Restricted Vocabulary - Limitation
DE PROFUNDIS
There is a stubble field on which a black rain falls. There is a tree which, brown, stands lonely here. There is a hissing wind which haunts deserted huts - how sad this evening. Past the village pond the gentle orphan still gathers scanty ears of corn. Golden and round her eyes are gazing in the dusk and her lap awaits the heavenly bridegroom. Returning home shepherds found the sweet body decayed in the bramble bush. A shade I am remote from somber hamlets. The silence of God I drank from the woodland well. On my forehead cold metal forms. Spiders look for my heart. There is a light that fails in my mouth. At night I found myself upon a heath, thick with garbage and the dust of stars. In the hazel copse crystal angels have sounded once more.
Georg Trakl (1887-1914)
Language
o Words are not mathematical variables
o Meaning is generated on the pragmatic (contextual) level – not semantic?
o The meaning of a word is its use in the language. (Ludwig Wittgenstein, Philosophical Investigations, 43)
Could LOM be formulated in RDF?
o Sure – everything can be (somehow) formulated in RDF.
o Could LOM be effectively/usefully formulated in RDF?
o Only if the “restricted vocabulary conflict” is successfully solved
o This is however true of every Semantic Web application
Thank YouNahum Korda