the role of simulation in dealing with complexity · the role of simulation in dealing with...
TRANSCRIPT
The Role of Simulation in dealing with complexity
Research School of Computer Science
College of Engineering and Computer Science
ENGN2219/COMP6719 – 2019
Agenda …
• Thinking about complexity– Dave Snowden’s Cynefin Framework
• Dealing with complexity– System Dynamics– Boyd’s OODA loop
• The role of simulation– Brooks’ Law example
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Thinking About Complexity…
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Thinking about complexity …
• The Cynefin sense-making framework– Pronounced “KUN-iv-in” (It’s a Welsh word!)
– Created in 1999 by Dave Snowden– http://cognitive-edge.com
• We require different kinds of thinking for– Obvious (Simple) Systems
– Complicated Systems– Complex Systems
– Chaotic Systems
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Unpredictable
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Predictable
The Cynefin Sense-making Framework
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Pre
dict
able
Unpredictable
The Cynefin Sense-making Framework
Complicated
Simple (obvious)
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Pre
dict
able
Complex
The Cynefin Sense-making Framework
Complicated
Simple (obvious)
Unp
redi
ctab
le
Chaotic
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Dealing with Complexity
Dealing with complexity
• Experimentation is at the core – Probe – with safe to run experiments– Sense – what works & what doesn’t– Respond – with emergent practices
• System Dynamics modeling and simulation can help
• We will also look at why Agility is important when dealing with complexity
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System Dynamics
• An approach to understanding the behavior of complex systems over time– Developed by Jay Forrester at MIT in the 1950’s
– Originally focussed on industrial processes
– Now widely used for policy analysis and design
• Systems are represented using– Causal Loop Diagrams (CLD)
– Stock and Flow Diagrams (SFD)
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CLD Example – using Exit Mould
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CLD Example – using Exit Mould
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SYMPTOMSYMPTOM
Mould on my bathroom tiles
CLD Example – using Exit Mould
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SYMPTOMSYMPTOM FIXFIX
+
Mould on my bathroom tiles
Apply Exit Mould and wipe down tiles
CLD Example – using Exit Mould
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SYMPTOMSYMPTOM FIXFIX
+
Mould on my bathroom tiles
Apply Exit Mould and wipe down tiles
-
CLD Example – using Exit Mould
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SYMPTOMSYMPTOM FIXFIX
UNEXPECTED CONSEQUENCEUNEXPECTED CONSEQUENCE
-
+
+
Mould on my bathroom tiles
Apply Exit Mould and wipe down tiles
delay
CLD Example – using Exit Mould
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SYMPTOMSYMPTOM FIXFIX
UNEXPECTED CONSEQUENCEUNEXPECTED CONSEQUENCE
-
+
+
Mould on my bathroom tiles
Apply Exit Mould and wipe down tiles
Exit Mould damages grout and tile surface
CLD Example – using Exit Mould
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SYMPTOMSYMPTOM FIXFIX
UNEXPECTED CONSEQUENCEUNEXPECTED CONSEQUENCEPROBLEMPROBLEM
-
+
+
+
Mould on my bathroom tiles
Apply Exit Mould and wipe down tiles
Exit Mould damages grout and tile surface
Damage encourages growth of deep mould
CLD Example – using Exit Mould
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SYMPTOMSYMPTOM FIXFIX
UNEXPECTED CONSEQUENCEUNEXPECTED CONSEQUENCEPROBLEMPROBLEM
-
+
+
+
+
Mould on my bathroom tiles
Apply Exit Mould and wipe down tiles
Exit Mould damages grout and tile surface
Damage encourages growth of deep mould
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“Fixes That Fail”
This is an example of a System Archetype
(a common pattern of behaviour)
Other Fixes that Fail …
• The war on terror
• Building freeways• Borrowing money to pay interest• Cutting maintenance and repair costs
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Dealing with a staff shortage …
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SYMPTOMSYMPTOM
Staff Shortage(cannot employ new people)
Dealing with a staff shortage …
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SYMPTOMSYMPTOM FIXFIX
+
Staff Shortage(cannot employ new people)
Dealing with a staff shortage …
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SYMPTOMSYMPTOM FIXFIX
+
Increase overtimeStaff Shortage(cannot employ new people)
Dealing with a staff shortage …
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SYMPTOMSYMPTOM FIXFIX
-
+
Increase overtimeStaff Shortage(cannot employ new people)
Dealing with a staff shortage …
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SYMPTOMSYMPTOM FIXFIX
UNEXPECTED CONSEQUENCEUNEXPECTED CONSEQUENCE
-
+
+
Increase overtimeStaff Shortage(cannot employ new people)
Dealing with a staff shortage …
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SYMPTOMSYMPTOM FIXFIX
UNEXPECTED CONSEQUENCEUNEXPECTED CONSEQUENCE
-
+
+
Increase overtime
Physical and mental health issues
Staff Shortage(cannot employ new people)
Dealing with a staff shortage …
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SYMPTOMSYMPTOM FIXFIX
UNEXPECTED CONSEQUENCEUNEXPECTED CONSEQUENCEPROBLEMPROBLEM
-
+
+
+
Increase overtime
Physical and mental health issues
Staff Shortage(cannot employ new people)
Dealing with a staff shortage …
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SYMPTOMSYMPTOM FIXFIX
UNEXPECTED CONSEQUENCEUNEXPECTED CONSEQUENCEPROBLEMPROBLEM
-
+
+
+
+
Increase overtime
Physical and mental health issues
Increased sick leave
Staff Shortage(cannot employ new people)
There are many such archetypes …
• System Archetypes describe patterns of behavior that surface in many different domains
• They help us– think about the possible behavior of complex systems
– understand why a complex system behaves the way it does, and
– identify things we can do to change that behavior (ie. the things that work and don’t work).
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The need for agility
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John Boyd
• Fighter pilot
• Military, sport and business strategist
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Boyd’s OODA Loop• A continuous process of learning and change in
competitive environments
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Speed is the key to success
• Success comes from getting around your OODA loop more quickly than your competitor– Business, Nature, Sport, Politics …
• If your competitor is quicker than you:– Your competitor's behavior will eventually appear chaotic – you will be
confused
– You will make bad decisions - based on ‘Orientation’ and ‘Observations’ that are no longer valid
– You will lose or fail
• Complex systems often evolve rapidly– You need to experiment, learn and act quickly
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The role of simulation
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How can simulation help
• We can simulate the behavior of complex systems– eg. System Dynamics Stock & Flow models
• We can do this quickly– In order to get through our OODA loop quickly
• We can run many simulations based on different parameters– That is, we can run a series of different ‘experiments’
– To find out what works & what doesn’t
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SFD Simulation Example - Brooks’ Law
• Fred Brooks– Turing Award 1999
– Author of “The Mythical Man-Month”
– Author of “No Silver Bullet”
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SFD Simulation Example - Brooks’ Law
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“Adding manpower to a late software project makes it later.”
Brooks’ Law
● Note that in his book ‘The Mythical Man-Month’, Brooks says that this law is an ‘outrageous oversimplification’.
● In reality, adding people to a project is a complex problem
● We can explore this problem using System Dynamics and Simulation.
SFD Simulation Example - Brooks’ Law
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https://insightmaker.com/insight/4648/Clone-of-Brooks-Law
SFD Simulation Example - Brooks’ Law
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• No new developers at day 100
SFD Simulation Example - Brooks’ Law
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• 5 new developers at day 100
SFD Simulation Example - Brooks’ Law
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• 15 new developers at day 100
SFD Simulation Example - Brooks’ Law
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• 15 new developers at day 100, decreased communications
SFD Simulation Example - Brooks’ Law
• But, how do we reduce communication?– Fewer meetings?
– Restrictions on email use?
– ...
• … and what are the consequences?– More mistakes?
– Duplication of work?
– ...
• Additional complexity …– Need to add these aspects to the model
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Exploring online SFD simulations
• https://insightmaker.com– Free & Open
– Supports Collaboration
– Huge repository of models you can play with
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Exploring online SFD simulations
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https://insightmaker.com/insight/12842/2014-Weather-Climate-Extreme-Loss-of-Arable-Land-and-Ocean-Fertility-The-World3-Model-Forecaster
Exploring online SFD simulations
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https://insightmaker.com/insight/101411/Air-Transport-Causal-Loop-Diagram
Exploring online SFD simulations
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https://insightmaker.com/insight/7682/Implementing-Chronic-Care-Management
Additional Material …
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System Dynamics– Wikipedia, “System Dynamics”
• https://en.wikipedia.org/wiki/System_dynamics
– Insight Maker, “Free modeling and simulation in your browser”• https://insightmaker.com
Cynefin Framework– Snowden, “Making Sense of Complexity”, Lean, Agile & Scrum Conference 2013
• https://www.youtube.com/watch?v=y6RfqmTZejU
– O’Sullivan, “Domain Driven Design for Everyone Else”, dev.to• https://dev.to/barryosull/domain-driven-design-for-everyone-else-a9
– Snowden and Boone, “A Leader’s Framework for Decision Making”, Harvard Business Review, Nov 2007
• https://hbr.org/2007/11/a-leaders-framework-for-decision-making
OODA Loops– Adolph, “What lessons can the agile community learn from a maverick fighter pilot?”,
Agile’06• https://ieeexplore.ieee.org/document/1667567/
Additional Material …
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Fred Brooks– Wikipedia, “Fred Brooks”
• https://en.wikipedia.org/wiki/Fred_Brooks
– Brooks, Fredrick P. (1975). “The Mythical Man-Month: essays in software engineering.” Reading, Massachusetts: Addison-Wesley.
• Amazon
– Brooks, F. P., Jr. (1987). “No Silver Bullet – Essence and Accidents of Software Engineering”. Computer. 20 (4): 10-19
• ACM
Questions ?
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