Transcript ESIP Winter ECC 2-3:30pm, Jan 5, 2012

Semantic Web Cluster and Energy and
Climate Cluster
ESIP Winter ECC 2-3:30pm, Jan 5, 2012
Peter Fox (RPI) [email protected]
Tetherless World Constellation
Basci unit of exchange – the
triple - example (linked data)
Subj
Pred
Obj
Pred
Pred
Subj
Obj
Subject-Predicate-Object
Note: namespaces, e.g. ‘rc’, ‘foaf’, ‘dbpedia’, etc. and types, e.g.
objects, data, functions, …
Best practice: put semantics between/ in your interfaces
Heath (2009) [annotated]
Semantic Web Layers
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http://www.w3.org/2003/Talks/1023-iswc-tbl/slide26-0.html, http://flickr.com/photos/pshab/291147522/
Working with knowledge
Expressivity
Implementability
Maintainability/ Extensibility
Working with knowledge
Query
Inference
Rule execution
Or it may be this …
Query
Inference
Rule execution
Expressivity/ Implementation
Declarative
Linked open data
URI/http/RDF *
Procedural
Ontology encoded
Ontology Spectrum
An ontology specifies a rich description of the
•
•
•
•
Terminology, concepts, nomenclature
Properties explicitly defining concepts
Relations among concepts (hierarchical and lattice)
Rules distinguishing concepts, refining definitions and relations
(constraints, restrictions, regular expressions)
relevant to a particular domain or area of interest.
www.ksl.stanford.edu/people/dlm/papers/ontologies-come-of-age-abstract.html
Semantic Web Standards*
• Schema - RDFS (Resource Description Framework
Schema, 2004)
• Ontology - OWL 1.0 (Web Ontology Language, 2004)
• Query - SPARQL 1.0 (SPARQL Protocol and RDF
Query Language, 2008)
• OWL 2.0 (2009)
• Taxonomy - SKOS (Simple Knowledge Organization
System, 2009)
• Rules - RIF (Rule Interchange Framework, 2010)
• SPARQL 1.1 (2012?)
• NB. No service standards! But, many in use…
See http://www.w3.org/TR/owl-features/ section 2 for features
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and relation to RDF or OWL species
Query - SPARQL
• SPARQL has 4 result forms:
– SELECT – Return a table of results.
– CONSTRUCT – Return an RDF graph, based on
a template in the query.
– DESCRIBE – Return an RDF graph, based on
what the query processor is configured to return.
– ASK – Ask a boolean query.
• The SELECT form directly returns a table
• DESCRIBE and CONSTRUCT use the
outcome of matching to build RDF graphs.
http://www.dajobe.org/2005/04-sparql/SPARQLreference-1.8-us.pdf
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SPARQL Solution
Modifiers
• Pattern matching produces a set of solutions.
This set can be modified in various ways:
– Projection - keep only selected variables
– OFFSET/LIMIT - chop the number solutions (best
used with ORDER BY)
– ORDER BY - sorted results
– DISTINCT - yield only one row for one
combination of variables and values.
• The solution modifiers OFFSET/LIMIT and
ORDER BY always apply to all result forms.
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Rule Interchange
Format (RIF)
• Interlingua (similar to KIF)
• http://www.w3.org/2005/rules/wiki/RIF_
Working_Group
• Tools starting (just) to emerge
• http://www.w3.org/2005/rules/wiki/RIF_
FAQ
• Reality: SWRL, Jena, Jess, OWL 2-RL
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How we do things…
• Semantics require domain expertise,
• And a (or many) use case(s),
• And a methodology to proceed with
knowledge extraction
• In case you have not visited our page:
http://wiki.esipfed.org/index.php/Semant
ic_Web (it’s messy)
E.g. RPI/TWC Methodology …
• Use cases
• Stakeholders
• Distributed
authority
• Access control
• Ontologies
• Maintaining
Identity
Use Case example
• Plot the neutral temperature from the Millstone-Hill
Fabry Perot, operating in the non-vertical mode
during January 2000 as a time series.
• Plot the neutral temperature from the Millstone-Hill
Fabry Perot, operating in the non-vertical mode
during January 2000 as a time series.
• Objects:
– Neutral temperature is a (temperature is a) parameter
– Millstone Hill is a (ground-based observatory is a) observatory
– Fabry-Perot is a interferometer is a optical instrument is a
instrument
– Non-vertical mode is a instrument operating mode
– January 2000 is a date-time range
– Time is a independent variable/ coordinate
– Time series is a data plot is a data product
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Elements of KR in
Semantic Web
• Declarative Knowledge
• Statements as triples: {subject-predicate-object}
interferometer is-a optical instrument
Fabry-Perot is-a interferometer
Optical instrument has focal length
Optical instrument is-a instrument
Instrument has instrument operating mode
Instrument has measured parameter
Instrument operating mode has measured parameter
NeutralTemperature is-a temperature
Temperature is-a parameter
• A query: select all optical instruments which have operating
mode vertical
• An inference: infer operating modes for a Fabry-Perot
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Interferometer which measures neutral temperature
Information Modeling
• Conceptual
• Logical
• Physical
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Who we do this with
• ESIP as a whole – ESIP network,
FUNding Friday project, IT&I committee
• Internally
• IQ cluster
• PS cluster
• D cluster
• Past: Water Cluster, AQ Cluster
What is produced?
• Tutorials (both lecture style and handson), guides, etc.
• Ontologies (across the spectrum) with
community governance
• [Some] Technical infrastructure – test
bed(s), e.g. triple store, SPARQL
endpoint, …
• Applications
• Demonstrations
Data type and services
Data Quality Ontology
Development (Quality flag)
Working together with Chris Lynnes’s DQSS project, started from
the pixel-level quality view.
Data Quality Ontology
Development (Bias)
http://cmapspublic3.ihmc.us:80/servlet/SBReadResourceServlet
?rid=1286316097170_183793435_22228&partName=htmltext
Modeling quality
(Uncertainty)
Link to other cmap presentations of quality
ontology:
http://cmapspublic3.ihmc.us:80/servlet/SBRead
ResourceServlet?rid=1299017667444_189782
5847_19570&partName=htmltext
AeroStat Ontology
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Opportunities
• I’ll mention just a few (so remember)
– Tutorials (both lecture style and hands-on),
guides, etc.
– Ontologies (across the spectrum) with
community governance
– [Some] Technical infrastructure – test
bed(s), e.g. triple store, SPARQL endpoint,
…
– Applications
– Demonstrations
– Cool people ;-)
SWEET (2.3)
• http://sweet.jpl.nasa.gov/
• Mappings to CF
http://sweet.jpl.nasa.gov/
sweetCF.xls
• Governed via Cluster,
http://wiki.esipfed.org/ind
ex.php/SWEET_Governa
nce
Frameworks - DPSIR
Semantics of DPSIR?
CMIP5 catalog explorer
• … with Earth System Grid Federation
– Stage 1 – Catalog as linked data
• Visual exploration of a large graph (cf. Wed.
poster)
– Stage 2 – data as linked data
• For knowledge discovery…
Related
• CSML – Climate Science Markup
Language - http://csml.badc.rl.ac.uk/
• MOLES - Metadata Objects for Linking
Environmental Sciences http://proj.badc.rl.ac.uk/moles/wiki
Rules of Engagement
• Semantics require domain expertise,
• And a (or many) use case(s),
Contact
• [email protected]
• http://wiki.esipfed.org/index.php/Semant
ic_Web
• 4th Tuesday telecon 1500ET
• http://rtpnet.org/mailman/listinfo/esipsemanticweb
• http://rtpnet.org/pipermail/esipsemanticweb/ (archives)
Reference material
Data-InformationKnowledge Ecosystem
Producers
Consumers
Experience
Data
Creation
Gathering
Information
Presentation
Organization
Knowledge
Integration
Conversation
Context
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Producers
Consumers
Quality Control
Quality Assessment
Fitness for Purpose
Fitness for Use
Trustee
Trustor
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Quality & Bias assessment using
FreeMind
FreeMind allows capturing
various relations between
various aspects of aerosol
measurements, algorithms,
conditions, validation, etc.
The “traditional” worksheets
do not support complex
multi-dimensional nature of
the task
from the Aerosol Parameter Ontology
RDFS
• Note: XMLS not an ontology language
– Changes format of DTDs (document
schemas) to be XML
– Adds an extensible type hierarchy
• Integers, Strings, etc.
• Can define sub-types, e.g., positive integers
• RDFS is recognisable as an ontology
language
– Classes and properties
– Sub/super-classes (and properties)
– Range and domain (of properties)
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However
• RDFS too weak to describe resources in sufficient
detail
– No localized range and domain constraints
• Can’t say that the range of hasChild is person when applied to
persons and elephant when applied to elephants
– No existence/cardinality constraints
• Can’t say that all instances of person have a mother that is also a
person, or that persons have exactly 2 parents
– No transitive, inverse or symmetrical properties
• Can’t say that isPartOf is a transitive property, that hasPart is the
inverse of isPartOf or that touches is symmetrica
• Difficult to provide reasoning support
– No “native” reasoners for non-standard semantics
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– May be possible to reason via First Order axiomatisation
The OWL language:
• Three species of OWL
– OWL full is union of OWL syntax and RDF
– OWL DL restricted to FOL fragment (¼ DAML+OIL)
– OWL Lite is “easier to implement” subset of OWL DL
• Semantic layering
– OWL DL ¼ OWL full within DL fragment
– DL semantics officially definitive
• OWL DL based on SHIQ Description Logic
– In fact it is equivalent to SHOIN(Dn) DL
• OWL DL Benefits from many years of DL research
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–
–
–
Well defined semantics
Formal properties well understood (complexity, decidability)
Known reasoning algorithms
Implemented systems (highly optimized)
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W3C OWL 2 Documents
• Document Overview - The place to start – light introduction to OWL
2 and its relationship to OWL
http://www.w3.org/TR/owl2-overview/
• New Features and Rationale - More details of the new features in
OWL 2 along with their motivations
http://www.w3.org/TR/owl2-new-features/
• Primer - An introduction to OWL using a running example
http://www.w3.org/TR/owl2-primer/
• Quick Reference A brief synopsis of the features of OWL along with
links into relevant documents (both to user and specification documents)
http://www.w3.org/TR/owl2-quick-reference/
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Profiles
• OWL defines only one fragment (OWL Lite)
• OWL 2 defines three different fragments with useful
computational properties
– EL: polynomial time reasoning for schema and data Useful for ontologies with large conceptual part
– QL: fast (logspace) query answering using RDBMs via
SQL - Useful for large datasets already stored in RDBs
– RL: fast (polynomial) query answering using ruleextended DBs - Useful for large datasets stored as RDF
triples
SKOS properties
Simple Knowledge Organization System - W3C Recommendation Status on August
18, 2009 http://www.w3.org/2004/02/skos/
• skos:note
e.g. ‘Anything goes.’
• skos:definition
e.g. ‘A long curved fruit with a yellow skin and soft, sweet white flesh inside.’
• skos:example
e.g. ‘A bunch of bananas.’
• skos:scopeNote
e.g. ‘Historically members of a sheriff's retinue armed with pikes who escorted judges at assizes.’
• skos:historyNote
e.g. ‘Deleted 1986. See now Detention, Institutionalization (Persons), or Hospitalization.’
• skos:editorialNote
e.g. ‘Confer with Mr. X. re deletion.’
• skos:changeNote
e.g. ‘Promoted “love” to preferred label, demoted “affection” to alternative label, Joe Bloggs, 200508-09.’
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SKOS Vocabulary
Elements
•
•
•
•
•
•
skos:mappingRelation
skos:closeMatch
skos:exactMatch
skos:broadMatch
skos:narrowMatch
skos:relatedMatch
• skos:exactMatch is disjoint with each
of the properties skos:broadMatch
and skos:relatedMatch.
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SKOS 2
• Is an OWL ontology (but OWL-Full) so
use the subset that is OWL-DL (for
reasoning support)
• See:http://www.w3.org/TR/skosreference/
• http://swig.hpclab.ceid.upatras.gr/SKOS
/Skos2Owl2 (for example)
Editors
• Protégé (http://protege.stanford.edu)
• SWOOP (http://mindswap.org/2004/SWOOP; see
also http://swoop.sourgeforge.net )
• Altova SemanticWorks
(http://www.altova.com/download/semanticworks/sem
antic_web_rdf_owl_editor.html)
• SWeDE (http://owleclipse.projects.semwebcentral.org/InstallSwede.html
), goes with Eclipse
• NeON toolkit http://neon-toolkit.org/
• ThManager http://thmanager.sourceforge.net/
• TopBraid Composer and other commercial tools
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Triple Stores
• Jena (http://jena.sourceforge.net/) and
Jena/TBD
• SeSAME/SAIL (http://www.openrdf.org/)
• KOWARI (http://www.kowari.org/) ->
• Mulgara (http://www.mulgara.org/)
• Redland (http://librdf.org/index.html)
• Oracle (!)
• Virtuoso
• Allegrograph
• Many others (relational, object-relational)
• Joseki, e.g. SPARQL end-point
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Reasoners (aka Inference
engines)
• Pellet **
• Racer (and Racer Pro) **
• SHER (IBM)
http://www.alphaworks.ibm.com/tech/sher
• Medius KBS
• FACT++
• fuzzyDL
• KAON2
• MSPASS
• QuOnto
• Jess (for Rules)
• …
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Services, …
• Now 4 submissions to W3C
– OWL-S - http://www.w3.org/Submission/OWL-S
(updated journal publication http://springerlink.com/content/wp8q2133g5725340/ )
– SWSO/F/L - Semantic Web Services
Ontology/Framework/Language http://www.w3.org/Submission/SWSF/
– WSMO/X/L - Web Services Modeling
Ontology/Exection/Language http://www.w3.org/Submission/WSMX/
www.wsmo.org, www.wsmx.org
– SAWSDL - (WSDL-S)
• SADI - http://sadiframework.org/content/
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