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




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


Concern with definition goes back to ancient Greece (2)









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


How to write a definition (1)

• If a good one exists refer to it. See dictionaries

and ISO standards. Or try

google define:


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.


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.


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


Question 2.1: What is the super-class of Cardinal?

What is the super-class of Cardinal?


Choose one answer:

1. College of Cardinals2. pope3. high church-official


Answer 2.1: High Church-official - 3

Subject field: Roman Catholic Church



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?


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?


Answer to exercise 2.2

• Super-class:– Request or instruction

Purchase OrderPurchase Order

Request or InstructionRequest or Instruction

Purchase OrderPurchase Order

InstructionInstructionRequestRequest


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.


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


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


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


Question 2.3: multidimensional view of the concept VEHICLE

VEHICLE


LAND VEHICLE

WATER VEHICLE

AIR VEHICLE

MOTORIZED VEHICLE

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.


Answer 2.3

VEHICLE


LAND VEHICLE

WATER VEHICLE

AIR VEHICLE

MOTORIZED VEHICLE

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

concern with definition goes back to ancient greece (1)

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