Knowledge Representation Part I Ontology Jan Pettersen Nytun Knowledge Representation Part I, JPN, UiA1

S O P Outline Knowledge Ontology – Ontology in philosophy – Ontology in computer science – Different types of ontologies Levels of ontological precision Knowledge Representation Part I, JPN, UiA2

3 Knowledge facts/understanding about a particular subject Representation a symbol or thing which represents something else (refers to, stands for) is when we can not use the “original”, like things in the natural world or concepts when to use computer-understandable form AI require

S O P 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. Knowledge Representation Part I, JPN, UiA4 From Wikipedia, the free encyclopedia (Knowledge representation and reasoning)

S O P 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) Knowledge Representation Part I, JPN, UiA5

S O P Knowledge Engineering Knowledge Representation Part I, JPN, UiA6 Get knowledge about some subject and represent it in a computable form for some purpose. The knowledge engineer tells the system what is true.

S O P Knowledge Base Knowledge Engineering Continues… Knowledge Representation Part I, JPN, UiA7 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

S O P Outline Knowledge Ontology – Ontology in philosophy – Ontology in computer science – Different types of ontologies Levels of ontological precision Knowledge Representation Part I, JPN, UiA8

S O P What is an Ontology in Regard to Philosophy? 9 From Wikipedia, the free encyclopedia

S O P Smith [1] the essence of ontology: “provide a definitive and exhaustive classification of entities in all spheres of being.” 10 What is an Ontology in Regard to Philosophy? Continues…

S O P What is an Ontology in Computer Science? 11 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.

S O P What is an Ontology in Computer Science? … Continues 12 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

In computer science and information science, an ontology is… a practical application of philosophical ontology. 13 [Ref. Medical Informatics: Knowledge Management and Data Mining in Biomedicine]: From Wikipedia, the free encyclopedia: Types of Ontologies

S O P Types 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). Knowledge Representation Part I, JPN, UiA14

S O P Types of Ontologies… Continues Knowledge Representation Part I, JPN, UiA15 General ontologies represent knowledge at an intermediate level of detail independently of a specific task… theories of time and space, for example... [Ref. Medical Informatics: Knowledge Management and Data Mining in Biomedicine]:

S O P Types of Ontologies… Continues Knowledge Representation Part I, JPN, UiA16 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. [Ref. Medical Informatics: Knowledge Management and Data Mining in Biomedicine]:

S O P Types of Ontologies… Continues Knowledge Representation Part I, JPN, UiA17 …ontologies designed for specific tasks are called application ontologies. Conversely, reference ontologies are developed independently of any particular purpose… [Ref. Medical Informatics: Knowledge Management and Data Mining in Biomedicine]:

S O P Descriptive Ontology for Linguistic and Cognitive Engineering Knowledge Representation Part I, JPN, UiA18

S O P Outline Knowledge Ontology – Ontology in philosophy – Ontology in computer science – Different types of ontologies Levels of ontological precision Knowledge Representation Part I, JPN, UiA19

S O P Knowledge Representation Part I, JPN, UiA20 Catalog : A list of things.

S O P 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:

S O P A Taxonomy – also called a class hierarchy - organizes its data into categories and subcategories.

S O P 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).

S O P 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.

S O P Ontology Engineering as a Disiplin Studies the methods and methodologies for building ontologies. Knowledge Representation Part I, JPN, UiA26 Reuse? Enumerate Terms Define Classes Define Properties Define Constraints Create Instances Decide Scope Example of Process

S O P References 27 [1] Book: David Poole and Alan Mackworth, Artificial Intelligence: Foundations of Computational Agents, Cambridge University Press, 2010, 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 24 th 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