1. Pedro Andrade Gilberto Câmara
Sugarscape
Pedro Andrade
Gilberto Câmara

2. The Sugarscape Model
Building artificial societies that model certain characteristics of real ones

3. The Sugarscape Model: Rules
Agents
movement rule
sex rule
cultural transmission rule
Cells
sugar growth rule

4. Cells produce sugar: rule Gα
Each cell grows α units of sugar by time step up to capacity

5. Sugarscape: Agents consume sugar
Agents look for sugar to eat
Agents attributes (age, wealth)

6. Sugarscape: Simple agent
Look for a random neighbor
Moves there if it has more sugar than the current cell to eat.

7. More complex Agent
Look for a random neighbor and moves whenever it has more sugar than the current cell.
Initial wealth (sugar) between 5 and 25
Metabolism between 1 and 4 sugar per each step
Age starting with zero and increasing by one per time step
Die by age (maximum age between 60 and 100)
Die by absence of wealth
Whenever it dies, creates another agent and put it in a random cell

8. Sugar and Agents Cells = Sugar Level, Capacity, Growback rule (Gα)
Fixed: Metabolism, Vision
Variable: Location, Sugar holdings
Movement rule (M)

9. Agent metabolism
Agents burn a fixed (but different) β amount of sugar per unit time ( 1 ≤ β ≤ 4 )

10. Agent vision
Agents see in four directions with a random γ field of view ( 1 ≤ γ ≤ 4 )

11. Agents carry food with them
Agents have an initial quantity of food
They also carry food that has not been eaten

12. Agent movement rule
Look out as far as vision enables – find the closest empty place with the most sugar
Move there and get all the sugar

13. Agent survival Agents collect sugar and consume
When they have no sugar, they die

14. Sugarscape society Under {G∞ ,M} Immediate growback Natural Selection
Agents stick to the ridges of the sugarscape
Under {G1 ,M}
Constant growback (one unit per time)
Natural Selection is more pronounced
Two agent colonies – one in each mountain

15. Wealth Distribution Add a rule: Replacement (R[a,b])
Lorenz Curve and Gini Coefficient
Pareto’s law in action
Wealth under {G1 ,M, R[60,100]}
Symmetric  Poverty-skewed

16. Social Networks Neighbor connection network Netlogo model?
von Neumann (4) / Moore (8) neighborhoods
Netlogo model?

17. Migration Migration under {G1 ,M} Seasonal migration under {Sαβγ,M}
Netlogo model
Emergence – diagonal waves!
Seasonal migration under {Sαβγ,M}
Hibernators and Migrators
Pollution under {G1 , Pαβ, Dα,M}
Pollution only – forced off mountains, starvation
Diffusion – living on the edges, making things worse

18. Changes How to improve the movement to find more sugar?
What happens with the average wealth and average age when the number of agents grow?