September 25th, 2007 Real Collegio Carlo Alberto 1

Agent based simulation and electricity market

Pietro TERNA, Department of Economic and Financial Science,University of Torino

terna@econ.unito.it, http://web.econ.unito.it/terna    

Politecnico di Torino - Ceris – Hermes - AEITElectricity market performance under physical constraints

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Building models:

three ways

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Three different symbol systems:

• verbal argumentations

• mathematics

• computer simulation (agent based)

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How to use agents in simulation models:

a radical view

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The radical characterization of an ABM must be found

into the possibility of real – direct or indirect (via the environment) – interaction amid the agents …

avoiding simplifications coming from the use aggregate (simultaneous) equations (going back to the Walrasian auctioneer)

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Agent based simulation

and real world representation

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Social simulation as a computer based way

to execute complex mental experiments,

but also as a via to represent the complexity of real world

simulation = agent-based models

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A dictionary

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A dictionary, from Conte R, Edmonds B, Moss S., Sawyer R.K., Sociology and Social Theory in Agent Based Social Simulation: A Symposium Computational & Mathematical Organization Theory 7, 183-205,2001

“1. The purpose of Agent Based Social Simulation (ABSS) is to analyse the properties of social systems defined by dense patterns of interaction among autonomous, cognitive

individuals.2. The same modelling techniques that are intended to represent real social systems can

also represent software systems such as the Internet and large federated data bases populated by intelligent information agents or, indeed, any other large, complex multi agent system. Multi agent based simulations (MABS) of such systems share the techniques of ABSS.”

My note:

• we use frequently the name of Agent Based Model (ABM) or Agent Computational Ecomics (ACE) instead of ABSS;

• in computer science the attention is devoted to Multi Agent Systems, MAS; adding “simulation” we have MABS and, in some way, ABSS.

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A general structure for agent-based simulation models, the ERA scheme

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http://web.econ.unito.it/terna/ct-era/ct-era.html

NNCSGA

Avatar

ERA,

Environment,

Rules, Agents

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Tools

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Swarm, http://www.swarm.org

SLAPP, Swarm-Like Agent Protocol in Python, temporary at http://eco83.econ.unito.it/terna/slapp ; Python at www.python.org

JAS, http://jaslibrary.sourceforge.net/

Ascape, http://www.brook.edu/dynamics/models/ascape/

Repast, http://repast.sourceforge.net/

StarLogo, http://education.mit.edu/starlogo/

StarLogo TNG, http://education.mit.edu/starlogo-tng/

NetLogo, http://ccl.northwestern.edu/netlogo/

SDML (based upon SmallTalk, as a declarative programming tool): http://www.cpm.mmu.ac.uk/sdml/

See also ABLE, http://www.research.ibm.com/able/

JADE, http://jade.tilab.com/

or DAML, www.daml.org

didactical perspective

nearly videogames

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We have also specialized agent based simulators, like

jES and jESOFhttp://web.econ.unito.it/terna/jes/

a simulator useful to reproduce enterprises behavior

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The surprising world of the Chameleons, with SLAPP

From an idea of Marco Lamieri, a project work with Riccardo Taormina

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The reinforcement learning algorithm

A direct tool: the reinforcement learning. We have

a set of states S, related to an environment;

a set of possible actions A;

a set of scalar rewards, in .

At any time t we have an agent in a state st of S and we can chose the action a in A(st). After the action it will be in st+1 with a reward rt+1. Reward are summed over time with a discount rate factor. Our agent develops the capability of mapping all the possible actions A in a state S to all the related rewards.

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The metaphorical models we use here is that of the changing color chameleons

We have chameleons of three colors: red, green and blue

When two chameleons of different colors meet, they both change their color, assuming the third one (If all chameleons get the same color, we have a steady state situation)

The metaphor is interpreted in the following way: an agent diffusing innovation or ideas (or political ideas) can change itself via the interaction with other agents: as an example think about an academic scholar working in a completely isolated context or interacting with other scholars or with private entrepreneurs to apply the results of her work

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A simple rule for a complex environment

Let play

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Running or chasing for identity!

• Reinforcement learning and pattern recognition, with bounded rationality

• Agent brain built upon 9 Artificial Neural Networks

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The surprising world of the Chameleons, with NetLogo

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Electricity market

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Leigh Tesf

atsion work

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Leigh Tesf

atsion work

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Leigh Tesf

atsion work

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Leigh Tesf

atsion work

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Leigh Tesf

atsion work

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Leigh Tesf

atsion work

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Leigh Tesf

atsion work

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Leigh Tesf

atsion work

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From spin glasses to videogames:

representing our worlds and their complexity via the use of simple simulation tools, with agents

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Scratch

http://weblogs.media.mit.edu/llk/scratch/

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The credit multiplier (money_supply.sb)

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StarLogo TNG

http://education.mit.edu/starlogo/

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StarLogo TNG

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Sperimentiamo la complessità con StarLogo TNG

termites2

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Sperimentiamo la complessità con StarLogo TNG

Fish and Plankton

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Squeak

http://www.squeak.org/

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Second Life

http://secondlife.com/

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