CS483/683 - AI Programming

Lecture 1:Introduction to

Multi-Agent Systems

19 January 2010Instructor: Kostas Bekris

Computer Science & Engineering, University of Nevada, Reno

Multi-Agent Systems: Algorithmic, Game-theoretic and Logical Foundations

MAS

What are multi-agent systems

Very vague definition:A system composed of multiple interacting

intelligent agents

Multiple?Multiple?Intelligent Intelligent

Agent?Agent?Interacting?Interacting?

MAS

Intelligent Agents

How can we fully describe an AI problem?

MAS

Multiple Interacting Agents

MAS

Forms of Interaction

Treat other agents similarly to the environment:

•Sensing and observing the behavior of other agents

•Acting upon other agents

Aspects of interaction in the field of multi-agent systems:

•Reason about the decision-making process of other agents

•Communication

•Respect predefined “social laws” and protocols of interaction

- how can a team of agents make fair decisions (e.g., voting schemes)

MAS

Agent Relations

Multi-Agent System

Cooperative Agents(optimize a

common utility) Non-cooperative Agents(separate utilities)

Coalitional Agents(e.g. opposing teams

of agents)

Competing Agents(e.g., opposing utilities)

Agents withdiverging interests

MAS

Types of Problems

Agent Design

•How to design an agent that collaborates with other agents to solve a common task?

•How to design an agent that competes with other agents so as to be the winner?

•How to design an agent that operates efficiently in an environment where multiple other agents operate with divergent interests?

Mechanism Design

•How to design the entire system so that a common utility function is optimized even when each agent is “strategic” (i.e., aims to optimize its own utility?)

MAS

Topics of Research in MAS

Agent-oriented Software Engineering Beliefs, Desired and Intentions (BDI) Cooperation and Coordination Organization Communication Negotiation Distributed Problem Solving Multi-Agent Learning Scientific Communities Dependability and Fault-Tolerance

MAS

Example Applications

Autonomous Physical Devices

•Multi-robot teams

•Coordinated Defense / Space Exploration Systems

•Sensor Networks

•Transportation and Traffic

Simulation Environments

•Computer Games

•Scientific Simulation

Networking, Mobile Technologies and the Internet

•Automatic and Dynamic Load Balancing

•Self-healing networks

Financial / Economics problems

•Pricing, accounting and logistics

•Bidding mechanisms, negotiations, e-commerce, electricity/energy markets

MAS

Why do we need MAS?

Ubiquity

•Send sensors and robots everywhere

Fault-tolerance

•Make many small, cheap devices, instead of one large, expensive one

•If a single device fails, the system may continue operating

The real world is a huge Multi-Agent System

•We might have to simulate real-world MAS

•Or we might desire to exercise some control over them

For fun

•Computer games and games in general

For profit

•You have to compete to succeed

•And you have to understand the underlying MAS to be a good competitor

MAS

Objections to MAS

Isn’t it all just Distributed Systems / Networking?

•Systems can be self-interested

Isn’t is all just Artificial Intelligence?

•Communication and social aspects were typically ignored in classical AI

Isn’t it all just Economics / Game Theory?

•We must also come with algorithmic solutions to game theoretic problems

•Not all assumptions in Game Theory are always true (e.g., “perfect market”)

Isn’t it all Social Science?

•Artificial societies do not have to be built exactly like human and biological societies

MAS

Class Overview

Intro to Multi-Agent Systems

Distributed Path Planning

Distributed Constraint Satisfaction

Distributed Constraint Optimization•Belief Propagation

•ADOPT

1.Auctions

Coordination through Social Laws

and protocols

{red, blue, green}

{red, blue, green}{red, blue, green}

≠ ≠

≠

a

b c

d

s t

1

1

3

2

2

2

1

1

3

∞

∞

∞ ∞

∞

0

MAS

Class Overview

Games in Normal Form• Two-player, zero-sum games

• General-sum games

• Nash equilibria and strategies

Games in Extensive Form•Perfect-Information Games

•Imperfect Information

6.Behavioral Strategies

Richer representations of games•Bayesian games

•Communication and Signaling games

Multi-agent Resource Allocation•Auctions

Husband

Wife

Lethal Weapon

WondrousLove

LethalWeapon

2, 1 0, 0

WondrousLove

0, 0 1, 2

Early March:Proposal Presentation

and Report

Late April:Final Presentation

and Report