1. Semantic Web for Earth and Environmental Terminology (SWEET) Rob Raskin NASA/JPL July 20, 2006

2. Outline Why use ontologies? Why use ontologies? SWEET ontologies SWEET ontologies Update/community processes Update/community processes

3. Why Use Ontologies?

4. Let’s eat, Grandma. Let’s eat Grandma. Time flies like an arrow. Fruit flies like a pie. Semantic Understanding is Difficult! Variable t: temperature Variable t: time Sea surface temperature: measured 3 m above surface Sea surface temperature: measured at surface LA Times headline Data quality= 5 Major combat operations in Iraq have ended

5. Ontologies General definition: “all that is known” General definition: “all that is known” Computer science definition: Machine-readable definition of terms and how they relate to one another Computer science definition: Machine-readable definition of terms and how they relate to one another As with a dictionary, terms are defined in terms of other terms As with a dictionary, terms are defined in terms of other terms Provide shared understanding of concepts Provide shared understanding of concepts Enable deeper semantics than typical controlled vocabulary for machine-to-machine communications Enable deeper semantics than typical controlled vocabulary for machine-to-machine communications

6. Taxonomy vs. Ontology Taxonomy (librarian perspective) Taxonomy (librarian perspective) Subject Classification Subject Classification Children are subcategory, not necessarily subclass of parent concepts Children are subcategory, not necessarily subclass of parent concepts Example: Example: EarthScience>Meteorology>WeatherPersonalities>DaveJones EarthScience>Meteorology>WeatherPersonalities>DaveJones Used by: Library of Congress, Dewey Decimal System, Web OpenDirectory, GCMD Keyword Used by: Library of Congress, Dewey Decimal System, Web OpenDirectory, GCMD Keyword Ontology (knowledge engineer perspective) Ontology (knowledge engineer perspective) Children are subclasses of parent concepts Children are subclasses of parent concepts Parent properties inherited by children Parent properties inherited by children Multiple inheritance generally supported Multiple inheritance generally supported Scalable Scalable “New” concepts are often definable using multiple inheritance (e.g. Sea floor temperature) rather than creating a new definition “New” concepts are often definable using multiple inheritance (e.g. Sea floor temperature) rather than creating a new definition

7. XML-based Ontology Languages XML satisfies desired properties for language syntax XML satisfies desired properties for language syntax However, there are too many possible ways that XML tags can be named and used However, there are too many possible ways that XML tags can be named and used No standardization of XML tag meanings as in HTML ( pair => renders in bold) No standardization of XML tag meanings as in HTML ( pair => renders in bold) Additional standardized semantics needed to exploit shared understanding of concepts Additional standardized semantics needed to exploit shared understanding of concepts W3C has adopted specializations of XML that predefine particular tags W3C has adopted specializations of XML that predefine particular tags Resource Description Formulation (RDF) Resource Description Formulation (RDF) Ontology Web Language (OWL) Ontology Web Language (OWL)

8. Semantic Web Vision Web page creators place XML tags around technical terms on web pages Web page creators place XML tags around technical terms on web pages XML tags point to ontology where term is defined XML tags point to ontology where term is defined Search tools use this information to provide value-added services Search tools use this information to provide value-added services Common search engines (Google) use these capabilities only minimally, at present Common search engines (Google) use these capabilities only minimally, at present

9. Applications Software tools can find “meaning” in resources for Software tools can find “meaning” in resources for Discovery Discovery Fusion Fusion Lineage Lineage … Requirements Requirements Data products associated with objects in “science concept space” Data products associated with objects in “science concept space” Richer descriptions than DIFs Richer descriptions than DIFs Data services associated with objects in “service concept space” Data services associated with objects in “service concept space” Richer descriptions than SERFs Richer descriptions than SERFs Search/fusion tools that exploit ontologies Search/fusion tools that exploit ontologies

10. SWEET Ontologies

11. SWEET Comprehensive upper-level ontology of Earth system science concepts Comprehensive upper-level ontology of Earth system science concepts Initial emphasis on improving search for NASA Earth science data resources Initial emphasis on improving search for NASA Earth science data resources Provides common semantic framework for representing Earth science data, information and knowledge Provides common semantic framework for representing Earth science data, information and knowledge Populated manually initially from: Populated manually initially from: GCMD controlled and uncontrolled keywords GCMD controlled and uncontrolled keywords CF terms CF terms Funding provided by the NASA Earth Science Technology Office Funding provided by the NASA Earth Science Technology Office

12. Substances non-living Substances Living Physical Processes Earth Realm Physical Properties Time Natural Phenomena Human Activities Integrative Space Data SWEET Ontologies UnitsNumerics Auxiliary

13. SWEET is a Concept Space Enables scalable classification of Earth science and associated data concepts Enables scalable classification of Earth science and associated data concepts Captures scientific philosophies Captures scientific philosophies Reductionism (in orthogonal, facted ontologies) Reductionism (in orthogonal, facted ontologies) Holisism (in integrative, unifying ontologies) Holisism (in integrative, unifying ontologies) Uses standard language (OWL DL) Uses standard language (OWL DL) Enables domain specialists to expand and specialize the work of others Enables domain specialists to expand and specialize the work of others Enables concepts to be translatable into other languages/cultures using “sameAs” notions Enables concepts to be translatable into other languages/cultures using “sameAs” notions Enables use of reasoners and other standard ontology tools Enables use of reasoners and other standard ontology tools

14. Fragment of SWEET Atmosphere AtmosphereLayer Troposphere Tropopause Stratosphere isUpperBoundaryOfisLowerBoundaryOf subClassOf partOf PlanetaryLayer partOf 3DLayer subClassOf upperBoundary =50 km lowerBoundary =15 km primarySubstance =“air” sameAs= “Lower Atmosphere”

15. Science Ontology Classes Earth Realms Earth Realms Atmosphere, SolidEarth, Ocean, LandSurface, … Atmosphere, SolidEarth, Ocean, LandSurface, … Properties (includes default unit) Properties (includes default unit) temperature, composition, area, albedo, … temperature, composition, area, albedo, … Substances Substances CO2, water, lava, salt, hydrogen, pollutants, … CO2, water, lava, salt, hydrogen, pollutants, … Living Substances Living Substances Humans, fish, … Humans, fish, … Processes Processes Diffusion, absorption, … Diffusion, absorption, …

16. Integrative Ontology Classes Phenomena Phenomena ElNino, Volcano, Thunderstorm, Deforestation) ElNino, Volcano, Thunderstorm, Deforestation) Each has associated EarthRealms, PhysicalProperties, spatial/temporal extent, etc. Each has associated EarthRealms, PhysicalProperties, spatial/temporal extent, etc. Specific instances included Specific instances included e.g., 1997-98 ElNino e.g., 1997-98 ElNino Human Activities Human Activities Fisheries, IndustrialProcessing, Economics, Public Good Fisheries, IndustrialProcessing, Economics, Public Good History History State of planet or equipment State of planet or equipment

17. Data Ontology Classes Dataset characteristics Dataset characteristics Format, data model, dimensions, … Format, data model, dimensions, … Special values Special values Missing, land, sea, ice,... Missing, land, sea, ice,... Parameters Parameters Scale factors, offsets, … Scale factors, offsets, … Data services Data services Subsetting, reprojection, … Subsetting, reprojection, … Quality measures Quality measures

18. Properties Intervals Intervals hasUpperLimit, hasLowerLimit, hasUnit hasUpperLimit, hasLowerLimit, hasUnit Applicable to spectral range and vertically structured layers of the Earth Applicable to spectral range and vertically structured layers of the Earth Spatial relations Spatial relations northOf, above, insideOf, hasDirection northOf, above, insideOf, hasDirection Other numerical relations Other numerical relations hasCoordinate1, lessThan hasCoordinate1, lessThan

19. SWEET is Middleware The intention is for specialized user communities to extend its content The intention is for specialized user communities to extend its content SWEET provides the common sense knowledge of Earth system science that is common to all disciplines SWEET provides the common sense knowledge of Earth system science that is common to all disciplines Domain specialists need to add only the incremental knowledge over and beyond the basic Earth system science knowledge Domain specialists need to add only the incremental knowledge over and beyond the basic Earth system science knowledge Community can submit extensions back into SWEET Community can submit extensions back into SWEET “sameAs” tags can be tagged with your community name “sameAs” tags can be tagged with your community name

20. SWEET as an Upper Level Earth Science Ontology MathPhysicsChemistry Space Time Property EarthRealm Process, Phenomena Substance Data Stratospheric Chemistry Biogeochemistry Specialized domains import SWEET

21. Earth Science Ontologies Numerics are limited Numerics are limited No Cartesian product (multidimensional) space predefined No Cartesian product (multidimensional) space predefined No numeric relations (+,, …) No numeric relations (+,, …) Community conventions must standardize extensions to language Community conventions must standardize extensions to language

22. Update/Community Processes

23. SWEET Users ESML- Earth Science Markup Language ESML- Earth Science Markup Language ESIP - Earth Science Information Partner Federation ESIP - Earth Science Information Partner Federation GEON- Geosciences Network GEON- Geosciences Network GENESIS- Global Environmental & Earth Science Information System GENESIS- Global Environmental & Earth Science Information System IRI- International Research Institute (Columbia) IRI- International Research Institute (Columbia) LEAD- Linked Environments for Atmospheric Discovery LEAD- Linked Environments for Atmospheric Discovery MMI- Marine Metadata Initiative MMI- Marine Metadata Initiative NOESIS NOESIS PEaCE- Pacific Ecoinformatics and Computational Ecology PEaCE- Pacific Ecoinformatics and Computational Ecology SESDI- Semantically Enabled Science Data Integration SESDI- Semantically Enabled Science Data Integration VSTO- Virtual Solar-Terrestrial Observatory VSTO- Virtual Solar-Terrestrial Observatory

24. Community Objectives Enable domain specialists to use and extend SWEET content Enable domain specialists to use and extend SWEET content Enable SWEET ontology to be accepted as a community standard Enable SWEET ontology to be accepted as a community standard Submit SWEET to the NASA Earth Science Standards Process Group during 2007 Submit SWEET to the NASA Earth Science Standards Process Group during 2007

25. Collaboration Web Site Basics Basics Blog, wiki, moderated discussion board, version control, validation services Blog, wiki, moderated discussion board, version control, validation services Search across ontologies Search across ontologies Trace of dependencies across ontologies Trace of dependencies across ontologies RSS service to notify ontology developers when change has been made RSS service to notify ontology developers when change has been made Policy is to remove term only if absolutely necessary, to remain backward compatibility Policy is to remove term only if absolutely necessary, to remain backward compatibility Expansion into new domains Expansion into new domains Geology, upper atmosphere, hydrosphere Geology, upper atmosphere, hydrosphere Review board Review board

26. For more information… http://sweet.jpl.nasa.gov http://sweet.jpl.nasa.gov