1 © 2005-2006 The ATHENA Consortium. Concern with definition goes back to ancient Greece (1)...
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Transcript of 1 © 2005-2006 The ATHENA Consortium. Concern with definition goes back to ancient Greece (1)...
1© 2005-2006 The ATHENA Consortium.
Concern with definition goes back to ancient Greece (1)
Socrates: (470–399 B.C.)
“Now one should do, Agathon, as you did, first describing who Eros himself is and what sort
of character he has, and then going on to what he does.”1
Socrates: (470–399 B.C.)
“Now one should do, Agathon, as you did, first describing who Eros himself is and what sort
of character he has, and then going on to what he does.”1
Method: 1. categorize: Is Eros a god, a mortal or a daimon?2. characterize: Is Eros good? Bad? Beautiful?3. describe behavior: Is Eros helpful to men?
Method: 1. categorize: Is Eros a god, a mortal or a daimon?2. characterize: Is Eros good? Bad? Beautiful?3. describe behavior: Is Eros helpful to men?
1. Plato, Symposium, edited by C.J. Rowe, Aris & Phillips Classical Texts, 1998, p.771. Plato, Symposium, edited by C.J. Rowe, Aris & Phillips Classical Texts, 1998, p.77
2© 2005-2006 The ATHENA Consortium.
Concern with definition goes back to ancient Greece (2)
Socrates: (470–399 B.C.)
“Now one should do, Agathon, as you did, first describing who Eros himself is and what sort
of character he has, and then going on to what he does.”1
Socrates: (470–399 B.C.)
“Now one should do, Agathon, as you did, first describing who Eros himself is and what sort
of character he has, and then going on to what he does.”1
Method: 1. categorize: Is Eros a god, a mortal or a daimon?2. characterize: Is Eros good? Bad? Beautiful?3. describe behavior: Is Eros helpful to men?
Method: 1. categorize: Is Eros a god, a mortal or a daimon?2. characterize: Is Eros good? Bad? Beautiful?3. describe behavior: Is Eros helpful to men?
Plato learned this method from Socrates who learned it from Diotima.Plato learned this method from Socrates who learned it from Diotima.
“All of Western philosophy is but a footnote to Plato…”
-- Alfred North Whitehead
“All of Western philosophy is but a footnote to Plato…”
-- Alfred North Whitehead
1. Plato, Symposium, edited by C.J. Rowe, Aris & Phillips Classical Texts, 1998, p.771. Plato, Symposium, edited by C.J. Rowe, Aris & Phillips Classical Texts, 1998, p.77
3© 2005-2006 The ATHENA Consortium.
How to write a definition (1)
• If a good one exists refer to it. See dictionaries
and ISO standards. Or try
google define:
4© 2005-2006 The ATHENA Consortium.
How to write a definition (2)
• Otherwise choose a suitable method:– Intensional– Extensional– Ostensive– Ad-hoc– Theoretical– Operational– Genus (super class) and difference, the classic method
• Key: Determine the intension of the concept and include examples of how the term is used.
5© 2005-2006 The ATHENA Consortium.
Intension and Extension
• The intension of a concept is its set of distinguishing characteristics• It is essentially a formula for testing if something is an instance of the
concept. • The extension of a concept, on the other hand, is determined by its
intension, and is the set of all those classes and objects that each have the distinguishing characteristics of the concept.
6© 2005-2006 The ATHENA Consortium.
Intension, Extension of Cardinal
Subject field: Roman Catholic Church
INTENSION:is a high church-official; ranks just below the pope; and is appointed by the pope to membership in the College of Cardinals
EXTENSION: all the members of the College of Cardinals
7© 2005-2006 The ATHENA Consortium.
Question 2.1: What is the super-class of Cardinal?
What is the super-class of Cardinal?
INTENSION:is a high church-official; ranks just below the pope; and is appointed by the pope to membership in the College of Cardinals
Choose one answer:
1. College of Cardinals2. pope3. high church-official
8© 2005-2006 The ATHENA Consortium.
Answer 2.1: High Church-official - 3
Subject field: Roman Catholic Church
INTENSION:is a high church-official; ranks just below the pope; and is appointed by the pope to membership in the College of Cardinals
9© 2005-2006 The ATHENA Consortium.
Exercise 2.1
• 1. Pick out the intension of Purchase Order from the definition given below:
• Purchase order (subject field: SAP MM-PUR)• A request or instruction from a purchasing organization to a vendor
(external supplier) or a plant to deliver a quantity of material or to perform services at a certain point in time.
• 2. What is the super-class (genus) of purchase order?
10© 2005-2006 The ATHENA Consortium.
Answer to exercise 2.1 and new question 2.2
• Distinguishing characteristics:– A purchase order is a request or instruction– It is given by a purchasing organization– It is given to a vendor (external supplier) or a plant– It specifies either the delivery of a quantity of material at a
certain point in time or the performance of services at a certain point in time
• Super-class:– Request or instruction
• How would you draw a subtype graph relating purchase order to its super-class?
11© 2005-2006 The ATHENA Consortium.
Answer to exercise 2.2
• Super-class:– Request or instruction
Purchase OrderPurchase Order
Request or InstructionRequest or Instruction
Purchase OrderPurchase Order
InstructionInstructionRequestRequest
12© 2005-2006 The ATHENA Consortium.
How to write a definition, extensional
• If a good one exists refer to it. See dictionaries and ISO standards. • Otherwise choose a suitable method:
Intensional– Extensional– Ostensive– Ad-hoc– Theoretical– Operational
Genus (super class) and difference, the classic method
A vertebrate is a mammal, reptile, amphibian, fish or bird.A vertebrate is a mammal, reptile, amphibian, fish or bird.
13© 2005-2006 The ATHENA Consortium.
How to write a definition: ostensive
screw – In shipbuilding:“A revolving device that drives a ship throughthe water, consisting of two or more blades”
screw – In shipbuilding:“A revolving device that drives a ship throughthe water, consisting of two or more blades”
screw: thisscrew: this
screw: this kind of devicescrew: this kind of device
14© 2005-2006 The ATHENA Consortium.
How to write a definition: what was covered so far
• If a good one exists refer to it. See dictionaries and ISO standards.• Otherwise choose a suitable method:
Intensional
Extensional
Ostensive– Ad-hoc– Theoretical– Operational
Genus (super class) and difference, the classic method
15© 2005-2006 The ATHENA Consortium.
Multiple Viewpoints of the Concept VEHICLE
VEHICLE
LAND VEHICLE
WATER VEHICLE
AIR VEHICLE
VEHICLE
NON MOTORIZEDVEHICLE
MOTORIZED VEHICLE
VEHICLE
CARGO VEHICLE
PASSENGER AND CARGO VEHICLE
PASSENGER VEHICLE
D1 – By medium of transportation
D2 – By method of propulsion
D3 – By principal type of load carried
16© 2005-2006 The ATHENA Consortium.
Question 2.3: multidimensional view of the concept VEHICLE
VEHICLE
NON MOTORIZEDVEHICLE
LAND VEHICLE
WATER VEHICLE
AIR VEHICLE
MOTORIZED VEHICLE
CARGO VEHICLE
PASSENGER AND CARGO VEHICLE
PASSENGER VEHICLE
CAR AIRPLANE
D1
D2
D3
DIMENSIONS:D1 – By medium of transportationD2 – By method of propulsionD3 – By principal type of load carried
Give a definition of car based on this diagram.
17© 2005-2006 The ATHENA Consortium.
Answer 2.3
VEHICLE
NON MOTORIZEDVEHICLE
LAND VEHICLE
WATER VEHICLE
AIR VEHICLE
MOTORIZED VEHICLE
CARGO VEHICLE
PASSENGER AND CARGO VEHICLE
PASSENGER VEHICLE
CAR AIRPLANE
D1
D2
D3
DIMENSIONS:D1 – By medium of transportationD2 – By method of propulsionD3 – By principal type of load carried
a car is a motorized vehicle for transporting passengers by land