Agent-based model of a simple stable economy Alexandre Lomovtsev Advisor: Dr. Russell Abbott, Ph.D. California State University, Los Angeles Department of Computer Science CSULA

Outline Background Model Design Modeling Environment Model Implementation (demo.)

Introduction Role of the economy models economic forecasting for given situation simulating changes and estimating possible impact; testing economical ideas and choices

Introduction Basic economic models supply-driven (depending on the supplies available) demand-driven (depending on the demand for own services)

Introduction Alternative energy flow Traditional monetary flow

Model Design: entities Source  Unlimited energy resource Sink  Consumed energy and items Agents  Entities performing all production and consumption activities in the system Objects/Items  Entities representing products and services Minimal variety of entities:

Model Design: network Energy consumption Goods production Source Agent Object Sink

Model Design: dynamics Consume Energy Sell Goods Produce Goods

Model Design: dynamics Consume Energy Sell Goods Produce Goods Verify the energy level Purchase more energy if needed Find buyer Check buyer’s solvency Perform transaction Verify that required supplies are in the stack Buy supplies if needed Buy energy if needed Produce item

Model Design: limitations Limited and fixed capacities of the Energy storage; same is for Supplies and Goods stacks. Limited life-span of agents; dying agents are being reborn, so the number of agents in the model remains constant. Limited and fixed variety of objects; no entities of new kind will be created in the model.

NetLogo  multi-agent system  simple environment  sufficient visualization  easy learning curve  extensions support (written in Java) Modeling Environment

NetLogo Main entities – agents  patches (stationary agents)  turtles (dynamic agents)  links (connecting two turtles)  observer – environment control  breeds – defined by the user Instructions  primitives – built into NetLogo  procedures – implemented by the user Variables  global  own by agents (built-in and user-defined)  local – defined in the scope of methods or loops

Model Implementation Objects  id  price  age  final  raw*  energy  work  dependencies  quantity

Model Implementation Nodes  energy  money  age  Accumulativeness (0…40%)  Advancement  goods  supplies  stack-out  stack-in  buyers  sellers

Model Implementation Sources  intensity (amount of energy per time interval) Sinks  energy (amount of energy finally consumed)

Constraints  no consuming own products  must be able to produce goods and consume products of other nodes Nodes Relationship receive energy consume energy share energy buy goods sell goods

Objects Relationship Constraints  at least one outgoing link and no incoming links for raw objects  at least one incoming link and no outgoing links for final objects  both incoming and outgoing links for other objects

Objects Relationship

Model Interface

References Abbott, R.J., “An agent-based model of a simple stable economy”, Retrieved 06/01/2011 from Project_ideas/An_agent- based_model_of_a_simple_stable_economy NetLogo User Manual: NetLogo Dictionary, Retrieved 06/01/2011 from Wikipedia, Energy Conversion Efficiency, Retrieved 06/01/2011 from #Example_of_energy_conversion_efficiency