Logics for Data and Knowledge
Representation
Towards Infrastructure, Methodology and Principles for Ontology
Development
Fausto Giunchiglia and Biswanath Dutta
Fall - 2011
Outline
 Introduction
Knowledge Representation (KR)
 Ontology

 Domain
 Facet
 DERA
 Mapping
 Methodology
 Principle
 Demo
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: Domain Modeling
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Knowledge Representation (KR)

“…is about building models of the world, of a particular
domain or problem, which allow automatic reasoning
and interpretation”
 Fundamental

3
Goal
is to represent knowledge in a manner that facilitates
inferencing new knowledge (i.e. drawing conclusions)
from the knowledge base
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Knowledge Representation Properties
 According
to (Crawford & Kuipers, 1990):
It must have a reasonably compact syntax.
 It must have a well defined semantics so that one can
say precisely what is being represented.
 It must have sufficient expressive power to represent
human knowledge.
 It must have an efficient, powerful, and understandable
reasoning mechanism
 It must be usable to build large knowledge bases.

Crawford, J. M. & Kuipers, B. (1990). ALL: Formalizing Access Limited Reasoning. Principles of semantic networks: Explorations in
the representation of knowledge, Morgan Kaufmann Pub., 299-330.
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Knowledge Representation Issues
 KR
issues:
How do people represent knowledge?
 What is the nature of knowledge?
 Do we have domain specific schema or generic, domain
independent schema?
 How much it needs to be expressive?

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Ontology
 “formal,
explicit specification of a shared
conceptualisation” – Gruber, 1993
 Models
a domain consisting of shared vocabulary with
the definition of objects and/or concepts and their
properties and relations
 A structural

used as a form of KR in the fields like, AI, SW, Lib. Sc., Inf.
Architecture, etc.
 Ontology
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framework for organizing information, and
as a language resource
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Ontology Properties
 Some
of the ontological properties are:

Extendable

Reusable

Flexible
Robust
…

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Domain
 An
area of knowledge or field of study that we are
interested in or that we are communicating about
 Example:
Computer science, Artificial Intelligence, Soft computing,
Social networks, …Library science, Mathematics,
Physics, Chemistry, Agriculture, Geography, …
 Music, Movie, Sculpture, Painting, …Food, Wine,
Cheese, …Space,…

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Domain (contd…)
 A domain
can be decomposed into its several
constituents, and
 Each of them denotes a different aspect of entities
 An
example from Space domain: by region, by body
of water, by landform, by populated places, by
administrative division, by land, by agricultural land,
by facility, by altitude, by climate,…
 Each
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of these aspects is called facet
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Facet
A
hierarchy of homogeneous terms describing an
aspect of the domain, where each term in the
hierarchy denotes a different concept
 E.g.,
Body of water(e.g., River, Lake, Pond, Canal), Landform
(e.g., mountain, hill, ridge), facility (e.g., house, hut,
farmhouse, hotel, resort), etc.
 language facet (e.g., English, Hindi, Italian,), property
facet, author facet, religion facet (e.g., Christian, Hindu,
Muslim), commodity facet, etc.

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DERA
 Is
a Facet based knowledge organization framework
 It is is independent from any specific domain
 Allows building domain specific ontologies
 Is logically sound
 Has mapping to Description Logic
 Decidable
 Designed
11
by the UniTn KnowDive group
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DERA Surface Structure
 In
the surface level, it has the following components:
D – Domain
 E – Entity
 R – Relation
 A – Attribute

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Domain (D)

A DERA domain is a tuple of,
D = <E, R, A>
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Entity (E)
 an
elementary component that consist of entity
classes and their instances, having either perceptual
correlates or only conceptual existence in a domain
in context
E = <{C} + {E'}>
 Where,
C = Entity class – consists of core classes representing
the entities;
 E' = Entity (also called object) – consists of real world
named entities, that is the instantiation of the entity
classes C.

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Entity (E) (contd…)
 Entity
class (C) :
Represents the essence of the domain under
consideration;
 Consists of the core classes representing a domain in
context
 E.g., Consider the following classes in context of Space
domain:


15
Mountain, Hill, Lake, River, Canal, Province, City, Hotel,...
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Entity (E) (contd…)
 Entity
(E') :
Are the real world named entities
 An extension of the real world entities


E.g.,

16
The Himalaya, Monte Bondone, Lake Garda, Trento, Povo, Hotel
America,...
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Entity (E) (contd….)
E.g., An example from a domain Space
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Relation (R)
 An
elementary component consists of classes
defining the relations between entities
R = <{r}>
 A relation
is a link between two entities (E')
 Builds a semantic relation between the entities
 E.g.,

18
Some relations (spatial) from Space domain: near,
adjacent, inside, before, center, sideways, etc.
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Attribute (A)
 An
elementary component consists of classes
expressing the characteristics of entities
A = <{A'}, {C}>
 An
attribute is any property, qualitative, quantitative
or descriptive measure of an entity
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Attribute (A) (contd…)
 Datatype Attribute
(A'):

A datatype attribute includes the attribute classes that
accounts the quality or quantity of an entity within a
domain

E.g.,

latitude, longitude (of a place):


altitude (of a mountain):



8000ft, 2400m.
high, low
depth (of a lake):


20
450 N, 180 S
deep, shallow
100ft., 20m.
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Attribute (A) (contd…)
 Descriptive Attribute



It includes the attribute classes that describe the entities
under a domain in consideration
The value of a descriptive attribute could consists of a single
string or a set of strings
E.g.,

natural resource (of a place):



{Classical architecture, Greek architecture, Roman architecture, Bauhaus,
etc.}
history (of a place)


coal, natural gas, oil, …
architectural style (of a castle):

21
(C):
……….
climbing route (to a mountain)

……………….
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Mapping
 From
DERA to DL
Entity classes (C) -> Concepts
 Relation (R) -> Roles
 Datatype attribute (A') -> Roles
 Descriptive attribute (C) -> Roles
 Entity (E') -> Individuals

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Methodology
 Step
1: Identification of the atomic concepts
 Step 2: Analysis (per genus et differentiam)
 Step 3: Synthesis
 Step 4: Standardization
 Step 5: Ordering
 Following
the above steps leads to the creation of a
set of facets. They constitute a faceted
representation scheme for a domain
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Ontological Principle

Relevance (e.g.,breed is more realistic to classify the universe of cows
instead of by grade)

Ascertainability (e.g., flowing body of water)

Permanence (e.g., Spring- a natural flow of ground water)

Exhaustiveness (e.g., to classify the universe of people, we need both
male and female)

Exclusiveness (e.g., age and date of birth, both produce the same
divisions)

Context (e.g., bank, a bank of a river, OR, a building of a financial
institution)

Important: helps in reducing the homographs

Currency (e.g., metro station vs. subway station)

Reticence (e.g., minority author, black man)

Ordering

24
Important: ordering carries semantics as it provides implicit relations between
the coordinate terms
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Step 1: identification of the atomic concepts
 Sources
of the concepts
WordNet
 GeoNames (357/663 classes)
 TGN
 Literature

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Step 1: identification of the atomic concepts (2)
 Some






of the relevant sub-trees in WordNet are:
location
artifact, artefact
body of water, water
geological formation, formation
land, ground, soil
land, dry land, earth, ground, solid ground, terra firma
Note: not necessarily all the nodes in these sub-trees need to be part of
the space domain. For example, the descendants of artifact, like,
article, anachronism, block, etc. are not.
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Analysis
Mountain
•
•
•
the
well
elevated land
defined
formed
by
the
geological
formation
(where
geological
formation is a natural
phenomenon)
altitude
>500m
27
in
general
Hill
•
•
•
the
well
defined
elevated land
formed
by
the
geological formation,
where
geological
formation is a natural
phenomenon
altitude
<500m
in
River
Stream
general
•
a body of water
•
a body of water
•
a flowing
water
•
a flowing
water
•
no fixed boundary
•
no fixed boundary
•
confined within a bed
and stream banks
•
confined within a bed
and stream banks
•
larger than a brook
body
of
body
of
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Synthesis
Body of water
Landform
Flowing body of water
Stream
Brook
River
Stagnant body of water
Pond
Natural depression
Oceanic depression
Oceanic valley
Oceanic trough
Continental depression
Trough
Valley
Natural elevation
Oceanic elevation
Seamount
Submarine hill
Continental elevation
Hill
Mountain
28 * each term in the above has gloss and is linked to synonym(ous) terms in the knowledge base
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Facets and sub-facets

Space [Domain]

by geographical feature [Entity class]






by water formation
by land formation
by land
by administrative division
…
by relations [Relation]

spatial relation




functional relation (e.g., primary inflow, primary outflow)
…
by attribute

[Datatype attribute]





latitude
Longitude
dimension
…
[Descriptive attribute]






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direction, internal, external, longitudinal, sideways, etc.
Natural resource
Architectural style
Time zone
ph
History
…
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