# Complexity projects

- Game of Life
- Social distancing
- Crowd simulation
- Building evacuation
- SIR (epidemiology)

# A complex system has

- __A__daptation and learning
- __C__onnectedness
- __I__nterdependence
- __D__iversity

# Wolfram behaviours

- Stables
- Periodic
- Chaotic
- Complex (high info content)

# Misc

- Exploration versus exploitation
- Highest peak
- On a dancing landscape you can never stop exploring
- Black swan

# Emergence

- Complexity is an emergent property
- Stasis encourages exploration and vice versa
- Slime mold breaking symmetry
- Bottom-up and top-down emergence
- Power law distribution
- Long tail
- Weekly emerging, strongly emerging (never figure out)
- Preferential attachment model

# Agent-based models

- Fires in crowded buildings
- Epidemics
- Netlogo
- Good science and agent based models must simplify (abstract)

# Feedback and externality

Feedback is affecting the same action.

- Positive feedback yields tipping points
- Negative feedback yields stability
- Feedback and externality produce path dependence

# The tail wags the dog

- With complex systems the mean doesn’t matter: it’s the tails
- Segregation is emergent
- Tipping is one way only, segregation is stable

# Social randomness – coin flipping

Humans underestimate how long runs of the same side can occur randomly. If a person is playing the part of the coin and selects three heads, the fourth flip won’t be a 50/50 chance of heads or tails – whereas the result of a truly random process would not be affected by the previous flips.

- Coin flip return times
- Don’t allow system to build themselves without adding extra checks to limit large events
- Central limit theorem