Research challenges faced

1
Research challenges faced

• The Agent-based modelling framework required the
  following features
• Ability to run many millions of complex agents
• Should run on any supercomputer or desktop
  (Linux, Mac, Windows)
• Allows economists to design models with no
  knowledge of programming
• Strong testing techniques to assure quality
  most large scientific software has serious bugs
  Hatton 1997
• Ability to combine different models sharing
  agents in a coherent and correct way

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Basic philosophy of FLAME

• Agents defined as communicating X-machines
• X-machine concept introduced by Eilenberg 1974
  and then ignored until recently
• General computational model
• Intuitive and easy to use in many different
  applications
• Economics, biology, management, sociology
• Messages sent to message boards
• Agents are distributed across processors using
  new techniques
• Efficient implementation utilises the available
  hardware serial or parallel

3
What agents do?

• They have a memory it contains their identity,
  location, other information such as their assets,
  employment state etc.
• They have a state which determines what they can
  do next
• They can read messages sent to them
• They can write messages to other agents
• They can carry out other operations if these are
  permitted accept job offer, buy shares, apply
  for credit etc.

4
The X-machine
5
FLAME Block Diagram
X parser files
make
Libmboard
Model.xml
1-N Xml files
Xparser.exe
Main.exe
Functions.c
0.xml
Your files
Xparser files
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How do you define agents?

• Use XMML e.g.

etc.
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Firm in labour market state table
8
A firms functions

• Firm send vacancies. If additional workers are
  needed the firm sends vacancies messages
• especially the different wage offers for the
  different general skill groups.
• Firm send redundancies. If the firm wants to
  decrease the workforce it sends redundancies.
• Firm idle. Firm does nothing.
• Firm reads job applications sends job offer or
  rejection.
• Firm reads the application, ranks the applicants
  according to their general and specific skills
  and sends as many job offers to the first ranked
  applicants as the firm has vacancies to fill. The
  other applicants are refused.
• Firm read job responses. The firm reads the
  responses to their job offers and updates the
  number of employees and the number of vacancies.

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Firm messages
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Parallel implementation
Parallel agents grouped on parallel
nodes. Messages synchronised Message board
library allows both serial and parallel versions
to work
Implementation details hidden from
modellers System automatically manages the
simulation
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C. Greenhough, D. Worth