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02. November 2007
Florian Probst
Data and Knowledge Modelling for the Geosciences- Chris Date Seminar -
e-Science Institute, Edinburgh
Semantic Reference Spaces for Observations and Measurements
Florian Probst 2
... short version
Theory on how tocategorize Qualities („properties of things“) and how toname their magnitudes („property values“)
--> Ontologies
--> Semantics
Florian Probst 3
• Vision, Motivation, Problem (Where to go? Why? What‘s the problem?)
• Background (Semantics, Ontologies )
• Research Questions
• Assumptions (basis of the approach)
• Qualities and Quality Spaces (ontological part)
• Semantic Reference Spaces (semantic part)
• Unit of Measure
• Region Extension Quality
• Roles
• Summary and Future Work
Florian Probst 4
Vision, Motivation and ProblemVision:Answer questions (solve problems) based on information from distributed and heterogeneous information sources. --> knowledge infrastructure, e-science
Motivation:Sharing knowledge requires the ability to compare conceptualizations and the ability to communicate about the meaning of words.
Problem:Lack of methods to assess semantic interoperability of information sources.
? Gewässer
max. Tiefe in Meter
#A 30
#B 52
lake depth in inch
#1 0.11
#2 0.23
Florian Probst 5
Ontology
An ontology is a symbol system (= human made artifact) An IS ontology is a formal theory.
Information System Ontologies”An ontology is a formal and explicit partial account of a conceptualization.” (Guarino, 1998)
Conceptualization“world view”
Referent
Florian Probst 6
Focus
What are the basic building blocks of geospatial information?results of observations and measurements.
Focus on:unary qualities of physical entities
Examples:the height of a mountain the mass of an applethe volume of a lake
Florian Probst 7
Goal and Research Questions
If we want to communicate the meaning of words denoting observations results we need to answer:
• What is the ontological nature of an observation?
• How to explicate the conceptualization underlying an observation result?
• How to name an observation result?
--> Develop methods to identify commensurability of information sources.
Florian Probst 8
Assumptions"Stand alone ontologies" are not enough for comparing conceptualizations.
Foundational Ontology
commensurableOntology B
Ontology A
A foundational ontology is required
My work is based on DOLCE (www.loa-cnr.it/)
Florian Probst 9
measuring = approximatingperceiving = approximating
Endurants, Qualities and Magnitudes
Volume Quality Space
volume quality (understood as individual entity)physical
endurant
volume qualityhasQualityphysical
endurant
hasQuality
Magnitudes of qualities are structured in quality spaces.
10 cm3
Reference Space
hasQualityLocation
Florian Probst 10
Taxonomy of Quality Spacesquality space
composed quality space basic quality space
abstract basic quality space (non - perceivable magnitudes)
spatio temporal basic quality space (perceivable magnitudes)
cognitively composed quality space
circular spatio temporal basic quality space
circular a-b quality space
scientifically composed quality space
non-boundary open st-b-quality space
one-boundary open st-b-quality space
one-boundary open a-b quality space
non-boundary open a-b quality space
(time, 1D spatial location)
(length, area, volume)
(non-boundary) circular quality space
(hue, wind direction)
non-boundary open quality space
one-boundary open quality space
(time, 1D spatial location)
(length, area, volume)
(non-boundary) circular quality space
(hue, wind direction)
non-boundary open quality space
one-boundary open quality space
Florian Probst 11
Quality Spaces and Reference Spaces
1 a
How to associate a sign with a magnitude?
1 a 2 a 3 a
region called
0 a
Florian Probst 12
Elements of a Semantic Datum I
Florian Probst 13
Roles
• Roles are individual entities
• An entity can play roles.
• An entity does not loose its identity when it stops playing a certain role. --> any-rigid or non-essential
• A role allows to functionally characterize an entity
• Ontology engineering problem: At a certain stage anything seems to be a role.
Florian Probst 14
Position of the Grounding Region
Florian Probst 15
Elements of a Semantic Datum II• Grounding Magnitude
A grounding magnitude is defined by agreement of a community. An atomic quality region plays the role of a grounding magnitude.
• Grounding Reference Region Since a unit of measure maps to an atomic quality region, practically useful measurement is not yet possible. The grounding reference region extends the number of magnitudes that can be validly named from a single magnitude to a magnitude range. It is this extension that makes measurement possible.
• Region Extension Quality This kind of quality specifies the extent of the each non-atomic reference region in the reference space.
• Unit of Measure The previously agreed grounding magnitude grounds an atomic reference region.
• Sign for the Unit of Measure Any symbol can be used to denote the unit of measure, e.g. /1mm/. Note that the grounding magnitude gives meaning to this symbol.
• Position of the Unit of Measure within the Grounding Region Without an explicitly defined position of the unit of measure within the grounding region, the grounding region can map on different magnitude ranges
Florian Probst 16
ResultsThe presented theory provides answers on
• how to classify observable entities
• how to structure the magnitudes of qualities in a scientific as well as cognitive plausible way
• how to partition the structured magnitudes and how to name the
partitions.
+ Ontology for qualities, endurants and perdurants
+ Ontology for quality spaces
+ Semantic Reference Spaces
Theory of semantic reference systems for observations and measurements
Florian Probst 17
Future Work
• Formal Ontology
• Extend theory: Investigate relational qualities (relational moments) and roles.
• Usability
• Methods for supporting users in “learning” a formal ontology.
• Research idea: semantic annotation infrastructure
• Semantic Translation
• Research idea: Combine methods for semantic similarity measurement with semantic reference systems.
Florian Probst 18
Thanks for your attention!