Part I Ontology - grimstad.uia.no · S P O Knowledge Base Example: Family Information …Continues Knowledge Representation Part I, JPN, UiA 10 Given the right logical rules, then

Knowledge Representation

Part IOntology

Jan Pettersen Nytun

Knowledge Representation Part I, JPN, UiA 1

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OP Outline

• Knowledge

• Reasoning / logical Consequence

• Ontology

– Ontology in philosophy

– Ontology in computer science

– Different types of ontologies

• Levels of ontological precision



Knowledge

facts/understandingabout a particular subject

Representation

a symbol or thing which representssomething else (refers to, stands for)

isis

when we can not use the “original”, like things in the natural world or concepts

when to use

computer-understandable form

AI require

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Knowledge Representation (KR) is an

area of artificial intelligence research aimed

at representing knowledge in symbols to

facilitate inferencing from those knowledge

elements, creating new elements of

knowledge.


From Wikipedia, the free encyclopedia(Knowledge representation and reasoning)

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OP Knowledge Base

• A database for knowledge management

• It provides means for information to be:

– Collected

– Organized

– Shared, searched and utilized (new information

may be inferred)


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OP Knowledge Engineering


• Get knowledge about some subject and represent it in a computable form for some purpose.

• The knowledge engineer tells the system what is true.

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• Knowledge


• Ontology






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Knowledge Base

Asserted and Inferred Statements


The system knows how to infer new facts and solutions – the user may form questions and then the system gives answers.

Asserted Statements

Inferred Statements

Asserted Statements

Inferred Statements

Inferred statements comes as a logical consequence of the asserted statements

and logical rules

Entailment

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Knowledge Base

Entailment (Logical Consequence)

Example: Family Information


• Identify “something” as being Person: Person(Ola), Person(Kari), Person(Marie),

Person(Jan), …

• Gender of person: Female(Kari), Male(Ola), Female(Marie),

Male(Jan), …

• Who is parent to a person: Parent(Ola, Marie), Parent(Kari, Marie), …

Inferred StatementsAsserted Statements:

Person(Ola), Person(Kari),

Person(Marie),Person(Jan),

Female(Kari), …

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Knowledge Base

Example: Family Information … Continues


Given the right logical rules, then family relations can be derived:• Parent(x, y) and Female(x) Mother(x, y)• ?? Daughter (x, y) • ?? Brother(x, y)

Asserted Statements:

Person(Ola), Person(Kari),

Person(Marie),Person(Jan),

Female(Kari), Male(Ola),

Female(Marie), Male(Jan),

Parent(Ola, Marie),

Parent(Kari, Marie), …

Inferred Statements:

Mother(Kari, Marie), …

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Complex relations:

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• Knowledge


• Ontology






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What is an Ontology

in Regard to Philosophy?

13

From Wikipedia, the free encyclopedia

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Smith [1] the essence of

ontology:

“provide a definitive and

exhaustive classification

of entities in all spheres

of being.”

14

What is an Ontology in Regard to Philosophy? Continues…

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What is an Ontology

in Computer Science?

15

Knowledge represented in a formal way:- a hierarchy of concepts within a domain, - a shared vocabulary to denote the types,- properties and interrelationships of those concepts.

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What is an Ontology

in Computer Science? … Continues

16

An ontology is a specification of a conceptualization that is designed for reuse across multiple applications and

implementations. …a specification of a conceptualization is a written, formal description of a set of concepts and

relationships in a domain of interest.

Peter Karp (2000) Bioinformatics 16:269

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OPOntology vs Knowledge Base"

“The Artificial-Intelligence literature contains many

definitions of an ontology; many of these contradict

one another. … An ontology together with a set of

individual instances of classes constitutes a

knowledge base. In reality, there is a fine line

where the ontology ends and the knowledge base

begins.”

[http://protege.stanford.edu/publications/ontology_development/ontology101-noy-mcguinness.html]


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Not All Would Agree On The

Following:

• “An ontology is, very roughly, a formal representation of a domain of knowledge. It is an abstract entity: it defines the vocabulary for a domain and the relations between concepts, but an ontology says nothing about how that knowledge is stored (as physical file, in a database, or in some other form), or indeed how the knowledge can be accessed.

• A knowledge base is a physical artifact: it is a database, a repository of information that can be accessed and manipulated in some predefined fashion. The knowledge in a knowledge base can be said to be modeled according to an ontology.”

[http://answers.semanticweb.com/questions/21500/what-is-the-difference-between-knowledge-base-and-ontology]


In computer science and information science, an ontology is… a practical application of philosophical ontology.

19

[Ref. Medical Informatics: Knowledge Management and Data Mining in Biomedicine]:

From Wikipedia, the free encyclopedia:

Types of Ontologies

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OPTypes of Ontologies… Continues

An upper ontology - also called top-level

ontology or foundation ontology - describes the

most general concepts that are the same across

all knowledge domains (e.g., Entity).


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General ontologies represent knowledge at an intermediate level of detail independently of a specific task… theories of time and space, for example...


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Domain ontologies represent knowledge about a particular part of the world, such as medicine, and should reflect the underlying reality through a theory of the domain represented.


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…ontologies designed for specific tasks are called application ontologies. Conversely, reference ontologies are developed independently of any particular purpose…


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Descriptive Ontology for Linguistic and Cognitive Engineering


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• Knowledge


• Ontology






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Catalog: A list of things.

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A Glossary, also known as a vocabulary,… is an alphabetical list of terms in a

particular domain of knowledge with the definitions for those terms.

From Wikipidia:

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A Taxonomy – also called a class hierarchy - organizes its data into

categories and subcategories.

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From Wikipidia: In general usage, a thesaurus is a reference work that lists words

grouped together according to similarity of meaning (containing synonyms and sometimes antonyms).

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From Wikipidia: A database schema …is a structure described in a formal

language… and refers to the organization of data as a blueprint of how a database is constructed (e.g., database tables for Relational Databases).

From Wikipidia: In mathematics, an axiomatic system is any set of

axioms from which some or all axioms can be used in conjunction to logically derive theorems. A mathematical theory consists of an axiomatic system and all its derived theorems.

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Ontology Engineering

as a Discipline

Studies the methods and

methodologies for building

ontologies.


Reuse?

Enumerate Terms

Define Classes

Define Properties

Define Constraints

Create Instances

Decide Scope

Example of Process

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OP References

33

[1] Book: David Poole and Alan Mackworth, Artificial Intelligence: Foundations of

Computational Agents, Cambridge University Press, 2010, http://artint.info/

Sowa, John F. (2000) Knowledge Representation: Logical, Philosophical, and

Computational Foundations, Brooks/Cole Publishing Co., Pacific Grove, CA.

Artificial Intelligence: Structures and Strategies for Complex Problem Solving (Addison-

Wesley), George F. Luger

Smith Barry. Accessed 24th of March, 2013, Ontology: Philosophical and Computational.

http: //ontology.buffalo.edu/smith/articles/ontologies.htm

Quine WVO. On What There Is. Review of Metaphysics 1948;p. 21–38.

Knowledge Representation Part I, JPN, UiA

http://artint.info/

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Part I Ontology - grimstad.uia.no · S P O Knowledge Base Example: Family Information …Continues Knowledge Representation Part I, JPN, UiA 10 Given the right logical rules, then