The document discusses complexity theory in software development, focusing on concepts such as agents, landscapes, emergence, and criticality. It highlights the influence of interconnectedness and load dynamics, using examples like traffic behavior and ant colonies to illustrate complex adaptive systems. Additionally, the document touches on software architecture principles, including REST and HATEOAS, while acknowledging various sources and inspirations.

1. COMPLEXITY
THEORY SOFTWARE
DEVELOPMENT
and
@tlberglund
Wednesday, October 17, 12 1

2. Agents
Landscapes
Emergence
Complexity
Criticality
Connectedness
Wednesday, October 17, 12 2

3. Agents
Wednesday, October 17, 12 3

4. Agents are...
Simple
Interactive
Adaptive
Wednesday, October 17, 12 4

5. Why Does
TRAFFIC
Jam?
Wednesday, October 17, 12 5

6. Stuck
in TRAFFIC
Talking on cell
phone, not paying
attention...
I sure am in
all this
a hurry!
space! I'm'a
speed up.
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7. Stuck
TRAFFIC
in
maniAc!
Oh, my
bad.
@%$#%!
Wednesday, October 17, 12 7

8. Net
LOGO
http://ccl.northwestern.edu/netlogo/
Wednesday, October 17, 12 8

9. Net
LOGO
Wednesday, October 17, 12 9

10. Net
LOGO
Flocking
Alignment: a bird tends to move in the same
direction of nearby birds.
Separation: a bird will turn to avoid another bird
if they get too close.
Cohesion: a bird will tend to move towards other
nearby birds.
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11. Net
LOGO
Wednesday, October 17, 12 11

12. Agents
Landscapes
Emergence
Complexity
Criticality
Connectedness
Wednesday, October 17, 12 12

13. Landscapes
Wednesday, October 17, 12 13

14. Think of a
Problem
as a
SURFACE
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15. MT. FUJI
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16. Frederick
Winslow
TAYLOR
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17. RUGGED
LANDSCAPES
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18. Dancing
LANDSCAPES
Wednesday, October 17, 12 18

19. Agents
Landscapes
Emergence
Complexity
Criticality
Connectedness
Wednesday, October 17, 12 19

20. Criticality
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21. the Normal
DISTRIBUTION
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22. the Power Law
DISTRIBUTION
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23. Wednesday, October 17, 12
Rice PILES 23

24. Work
LOAD
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25. Work
LOAD
Wednesday, October 17, 12 25

26. Work
LOAD
Wednesday, October 17, 12 26

27. Work
LOAD
Wednesday, October 17, 12 27

28. Work
LOAD
Wednesday, October 17, 12 28

29. Work
LOAD
Wednesday, October 17, 12 29

30. Work
LOAD
Wednesday, October 17, 12 30

31. Work
LOAD
Wednesday, October 17, 12 31

32. Work
LOAD
Wednesday, October 17, 12 32

33. Work
LOAD
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34. Too much
Utilization leads to
CRITICALITY
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35. Agents
Landscapes
Emergence
Complexity
Criticality
Connectedness
Wednesday, October 17, 12 35

36. Connectedness
Wednesday, October 17, 12 36

37. A really basic refresher in
Graph
THEORY Seriously...BASIC.
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38. Degree 5
Degree 1
Degree 4
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39. To here
From here
Path Length= 3
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40. Network
FUNCTIONALITY
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41. Information
DIFFUSION depends on Path Length
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42. Robustness to
FAILURE depends on degree distribution
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43. Agents
Landscapes
Emergence
Complexity
Criticality
Connectedness
Wednesday, October 17, 12 43

44. Emergence
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45. Slime
Wednesday, October 17, 12
MOLD 45

46. Slime Mold Emergence
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47. Conway’s
Game
of
Wednesday, October 17, 12
LIFE 47

48. Gameof
Conway’s
LIFE
1. Any live cell with fewer than two live neighbours
dies.
2. Any live cell with more than three live neighbours
dies.
3. Any live cell with two or three live neighbors lives.
4. Any dead cell with exactly three live neighbors
comes to life.
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49. Wednesday, October 17, 12 49

50. Wednesday, October 17, 12 50

51. Wednesday, October 17, 12 51

52. Surprise!
it’s a
COMPUTER
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53. Von Neumann
ARCHITECTURE
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54. Wednesday, October 17, 12 54

55. Wednesday, October 17, 12 55

56. Ant
COLONIES
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57. Wednesday, October 17, 12 57

58. Proceed with
CAUTION
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59. Software as a
COMPLEX
Profession
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60. AGENT-
BASED
DECISION
MAKING
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61. Wednesday, October 17, 12 61

62. What kind of
Software
Architecture would look like an
ANT
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COLONY? 62

63. Wednesday, October 17, 12 63

64. Wednesday, October 17, 12 64

65. Hypertext as the
Engine
of
APPLICATION
STATE
http://bit.ly/HATEOAS
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66. the way
HATEOAS
Works
GET /sandwich
Service
Web Service
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67. HATEOAS
the way
Works
Service
400 ERROR
<link rel=”bread” />
<link rel=”ingredient” />
Web Service
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68. HATEOAS
the way
Works
POST /sandwich
bread=rye
Service meat=pastrami
Web Service
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69. HATEOAS
the way
Works
Service
201 OK
<link href=”sandwich”>
<link href=”eat” />
<link href=”side” />
Web Service
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70. Make me a
Add Toppings
Sandwich I make Give me a
sandwiches.
sandwich, and I
can decorate it
with toppings.
I exchange
sandwiches
I toast Federal
for
sandwichReserve
buns.Notes.
Checkout
Toast Bun
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71. REST done
RIGHT
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72. Class
Are your
Dependencies
like a
RICE PILE?
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73. Afferent
COUPLING
A class's afferent coupling is a measure of how many
other classes are coupled to it through method calls,
field accesses, inheritance, arguments, return
types, and exceptions.
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74. remember the Power Law
DISTRIBUTION
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75. grails-web
900
675
450
225
0
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76. Hibernate 3
1500
1125
750
375
0
Wednesday, October 17, 12 76

77. Spring 3 Core
300
225
150
75
0
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78. toward a
COMPLEX
THEORY of
SOFTWARE
DEVELOPMENT
Wednesday, October 17, 12 78

79. Agents
Landscapes
Emergence
Complexity
Criticality
Connectedness
Wednesday, October 17, 12 79

80. Thank You
Tim Berglund
tlberglund@github.com
@tlberglund
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81. ACKNOWLEDGMENTS
http://bit.ly/unde
rstanding-compl
exity
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82. Photo Credits
Slime Mold Cells
http://campus.queens.edu/faculty/jannr/Botany/images/slimies/slimeMolds/slimeMold1152.jpg
Car Top View
http://www.motiontrends.com/2006/m09/Volvo/C30.shtml
Ants
http://www.flickr.com/photos/binux/2495709841
Traffic Jam
http://www.flickr.com/photos/lynac/321100379/
Turning Machine
http://www.ecs.syr.edu/faculty/fawcett/handouts/webpages/CoreTechnologies.htm
VonNeumann Machine
http://en.wikipedia.org/wiki/File:Von_Neumann_architecture.svg
Ant Colony
http://www.bioone.org/doi/full/10.1672/1536-2442%282004%29004%5B0001%3ATNAOTF%5D2.0.CO%3B2
Mt. Fuji
http://www.flickr.com/photos/mtsn/229410448
Snowy Mountains
http://www.flickr.com/photos/huzhead/85362599
Portrait of Frederick Winslow Taylor
http://upload.wikimedia.org/wikipedia/commons/9/90/Frederick_Winslow_Taylor_crop.jpg
Female Velvet Ant (in Work Load Illustration)
http://www.flickr.com/photos/markop/1036891509
Frederick Hayek
http://www.lancs.ac.uk/staff/ecagrs/Hayek%20quotes.htm
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