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!