Creative Systems Engineering IEEE / INCOSE Presentation Walter Sobkiw November 17, 2009.
1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems...
-
Upload
alexandra-hammond -
Category
Documents
-
view
213 -
download
0
Transcript of 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems...
![Page 1: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/1.jpg)
1
On the Various Conceptualizations of Systems
…and Their Impact on the Practice of Systems Engineering
On the Various Conceptualizations of Systems
…and Their Impact on the Practice of Systems Engineering
2008 INCOSE Symposium
James N MartinTimothy L J Ferris
© 2008 The Aerospace Corporation & Timothy L J Ferris
![Page 2: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/2.jpg)
2
Systems Thinking
“A system is a way of looking at the world.”
“… a system, any system, is the point of view of one or several observers.”
“A system is a way of looking at the world.”
“… a system, any system, is the point of view of one or several observers.”
Gerald M. Weinberg (1975),An Introduction to General Systems Thinking
![Page 3: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/3.jpg)
3
Thing
System as a “Point of View”
Point of View
Image
Observer
![Page 4: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/4.jpg)
4
Two Observers Two SystemsTwo Observers Two Systems
Thing
Observers
Point of View
Image
![Page 5: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/5.jpg)
5
Some Recent History
• The Solar System (2005) The Sun plus 9 Planets
• The Solar System (2006) The Sun plus 8 Planets
![Page 6: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/6.jpg)
6
Our Choice…• The things we “put” into our System
– Are things of our own Choosing– Are there for the purpose of Understanding– Are not pre-determined by some magical “Rules of
Inclusion”
• We must choose Carefully– A wrong choice could lead to incorrect Understanding– We often don’t know a priori what is the best
Rule of Inclusion to use– May need to experiment with different possible
System boundaries & configurations
![Page 7: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/7.jpg)
7
![Page 8: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/8.jpg)
8
![Page 9: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/9.jpg)
9
![Page 10: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/10.jpg)
10
![Page 11: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/11.jpg)
11
![Page 12: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/12.jpg)
12
![Page 13: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/13.jpg)
13
A Common (Mis)Perception
System = Sum of Parts
That We Design & Build
![Page 14: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/14.jpg)
14
System Parts
![Page 15: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/15.jpg)
15
Parts – Also Known As…
• Subsystems
• Elements
• Products
• Devices
• Subassemblies
• Components
• Items
• Units
![Page 16: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/16.jpg)
16
What are the Parts of this System ?
• Camera Lens Assembly• Flash Device• Electronic Circuit• User Interface Unit
• Carrying Case• Shipping Container• Instructions• Technique for Holding• Extra batteries• Photo Printer• Patents
![Page 17: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/17.jpg)
17
We need to Imagine more than just the things we build…
![Page 18: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/18.jpg)
18
What Types of Parts Constitute a System?
Hardware and Software ??
Hardware and Software and People ??
![Page 19: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/19.jpg)
19
Types of System PartsTypes of System Parts
PATENT
BASICPART TYPES
BASICPART TYPES
HARDWARE SOFTWARE PERSONNEL FACILITIES
DATA MATERIALS SERVICES TECHNIQUES
![Page 20: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/20.jpg)
20
More Than Just Parts…
System = Sum of Parts
+ Interactions
![Page 21: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/21.jpg)
21
How many ways to Interact ?
![Page 22: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/22.jpg)
22
Which is the best way to Interact ?
??
![Page 23: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/23.jpg)
23
Beyond Interactions…
System = Sum of Parts
+ Interactions
+ Context
![Page 24: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/24.jpg)
24
Context 1
PARTPARTPART
PART
Context 2
PARTPARTPART
PART
![Page 25: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/25.jpg)
25
Beyond Context…
System = Sum of Parts
+ Interactions + Context
+ Actions
![Page 26: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/26.jpg)
26
Camera Actions
![Page 27: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/27.jpg)
27
Action Diagrams
![Page 28: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/28.jpg)
28
Context A
Action in Different Contexts
Action1
Action2
Context B
Action1
Action3
![Page 29: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/29.jpg)
29
Beyond Actions…
System = Sum of Parts
+ Interactions + Context
+ Actions + Relationships
![Page 30: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/30.jpg)
30
Relationship Types
• Interpersonal– Family, Friends, Social, Organizational, …
• Mathematical– Equality, Order, Topological, Functionality, …
• Cause-Effect– Event-Driven, Probabilistic, …
• Physical Properties– Forces, Fields, Chemical effects, …
![Page 31: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/31.jpg)
31
Entity-Relationship Pairs
Entity A
Entity B
Related to
Rain
Wet Ground
Causes
![Page 32: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/32.jpg)
32
Relationship Examples
Balls
Box
Inside
Road
Building
Brings traffic toand from
![Page 33: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/33.jpg)
33
Observing System Relationships
Observing System
Data Handling Systemprovides
data to
Userprovides info to
![Page 34: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/34.jpg)
34
Observing System Relationships
Observing System
Data Handling Systemprovides
data to
Userprovides info to
is type of
Stake-holder
has
Stakeholder Requirement
![Page 35: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/35.jpg)
35
Observing System Relationships
Observing System
Data Handling System
Environmental Phenomenon
provides data to
Basic Service Requirement
< drives
Userprovides info to
is type of
Stake-holder
has
Stakeholder Requirement
< drives< drives
![Page 36: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/36.jpg)
36
Observing System Relationships
Observing System
Data Handling System
Human
Environmental Phenomenon
Environmental Parameter
Sensing Element
Sensor
measures
is a
contains
characterizes
provides data to
Basic Service Requirement
< drives
Userprovides info to
is type of
Stake-holder
has
Stakeholder Requirement
< drives< drives
![Page 37: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/37.jpg)
37
Observing System Relationships
Observing System
Data Handling System
Human
Environmental Phenomenon
Environmental Parameter
Sensing Element
Sensor
Platform / Station
measures
is a
contains
characterizes
provides data to
Location
located at
MobileFixed
is
Space
Air
Ground
Ocean
Space
Air
Ground
Ocean
Basic Service Requirement
< drives
provides data directly to
Userprovides info to
is type of
Stake-holder
has
situated on
Stakeholder Requirement
< drives< drives
![Page 38: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/38.jpg)
38
Observing System Relationships
Larger System
Observing System
Data Handling System
Human
Environmental Phenomenon
Environmental Parameter
Sensing Element
Sensor
Platform / Station
part of
measures
is a
contains
characterizes
provides data to
Observation Control System
is controlled by
Location
located at
MobileFixed
is
Space
Air
Ground
Ocean
Space
Air
Ground
Ocean
Basic Service Requirement
< drives
provides data directly to
Userprovides info to
is type of
Stake-holder
has
Operator operated by
situated on
Support
supported by
Owner
owned by
Stakeholder Requirement
< drives< drives
![Page 39: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/39.jpg)
39
Observing System Relationships
Larger System
Observing System
Data Handling System
Human
Environmental Phenomenon
Environmental Parameter
Sensing Element
Sensor
Platform / Station
part of
measures
is a
contains
characterizes
provides data to
Observation Control System
is controlled by
Location
located at
MobileFixed
is
Space
Air
Ground
Ocean
Space
Air
Ground
Ocean
Basic Service Requirement
< drives
provides data directly to
Userprovides info to
is type of
Stake-holder
has
Operator operated by
situated on
Support
supported by
Owner
owned by
Stakeholder Requirement
< drives< drives
![Page 40: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/40.jpg)
40
System = Sum of Parts
+ Interactions + Context
+ Actions + Relationships
+ Destiny
And Finally…
![Page 41: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/41.jpg)
41
Destiny Impact
Purpose
![Page 42: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/42.jpg)
42
PICARD Theory of Systems
Parts
Interactions
Context
Actions
Relationships
Destiny
Holistic Image ofSystem =
From the Point of View of an ObserverFrom the Point of View of an Observer
![Page 43: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/43.jpg)
43
Thing
Systems are “Imaginary”
Point of View
Observer
Image
![Page 44: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/44.jpg)
4444
System – Seen by Operator
Larger System
Observing System
Data Handling System
Human
Environmental Phenomenon
Environmental Parameter
Sensing Element
Sensor
Platform / Station
part of
measures
is a
contains
characterizes
provides data to
Observation Control System
is controlled by
Location
MobileFixed
is
Space
Air
Ground
Ocean
Space
Air
Ground
Ocean
Basic Service Requirement
< drives
provides data directly to
Userprovides info to
is type of
Stake-holder
has
Operator operated by
situated on
Support
supported by
Owner
owned by
Stakeholder Requirement
< drives< drives
![Page 45: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/45.jpg)
4545
System – Seen by User
Larger System
Observing System
Data Handling System
Human
Environmental Phenomenon
Environmental Parameter
Sensing Element
Sensor
Platform / Station
part of
measures
is a
contains
characterizes
provides data to
Observation Control System
is controlled by
Location
MobileFixed
is
Space
Air
Ground
Ocean
Space
Air
Ground
Ocean
Basic Service Requirement
< drives
provides data directly to
Userprovides info to
is type of
Stake-holder
has
Operator operated by
situated on
Support
supported by
Owner
owned by
Stakeholder Requirement
< drives< drives
![Page 46: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/46.jpg)
4646
System – Seen by Developer
Larger System
Observing System
Data Handling System
Human
Environmental Phenomenon
Environmental Parameter
Sensing Element
Sensor
Platform / Station
part of
measures
is a
contains
characterizes
provides data to
Observation Control System
is controlled by
Location
MobileFixed
is
Space
Air
Ground
Ocean
Space
Air
Ground
Ocean
Basic Service Requirement
< drives
provides data directly to
Userprovides info to
is type of
Stake-holder
has
Operator operated by
situated on
Support
supported by
Owner
owned by
Stakeholder Requirement
< drives< drives
IF
IF IF IF
IF
IF
IF
IF
![Page 47: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/47.jpg)
4747
System – Seen by GEOSS
Larger System
Observing System
Data Handling System
Human
Environmental Phenomenon
Environmental Parameter
Sensing Element
Sensor
Platform / Station
part of
measures
is a
contains
characterizes
provides data to
Observation Control System
is controlled by
Location
MobileFixed
is
Space
Air
Ground
Ocean
Space
Air
Ground
Ocean
Basic Service Requirement
< drives
provides data directly to
Userprovides info to
is type of
Stake-holder
has
Operator operated by
situated on
Support
supported by
Owner
owned by
Stakeholder Requirement
< drives< drives
![Page 48: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/48.jpg)
4848
System – Seen by NOAA Director
Larger System
Observing System
Data Handling System
Human
Environmental Phenomenon
Environmental Parameter
Sensing Element
Sensor
Platform / Station
part of
measures
is a
contains
characterizes
provides data to
Observation Control System
is controlled by
Location
MobileFixed
is
Space
Air
Ground
Ocean
Space
Air
Ground
Ocean
Basic Service Requirement
< drives
provides data directly to
Userprovides info to
is type of
Stake-holder
has
Operator operated by
situated on
Support
supported by
Owner
owned by
Stakeholder Requirement
< drives< drives
![Page 49: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/49.jpg)
49
Systems Thinking
“A system is a way of looking at the world.”
“… a system, any system, is the point of view of one or several observers.”
“A system is a way of looking at the world.”
“… a system, any system, is the point of view of one or several observers.”
Gerald M. Weinberg (1975),An Introduction to General Systems Thinking
![Page 50: 1 On the Various Conceptualizations of Systems …and Their Impact on the Practice of Systems Engineering 2008 INCOSE Symposium James N Martin Timothy L.](https://reader036.fdocuments.in/reader036/viewer/2022081518/5514a771550346f06e8b5d49/html5/thumbnails/50.jpg)
50
Postscript
All models are wrong, some are useful– George Box
All systems are imaginary, some are useful– James Martin
Models can be used to facilitate the imaginationModels can be used to
facilitate the imagination