WELCOME TO ECONOMICS 1040:STRATEGY, CONFLICT & COOPERATION

Spring 2011W 5:30-7:30

53 Church St, L01Instructor: Robert Neugeboren

neugebor@fas.harvard.edu

Teaching Fellow: Rajiv Shankarrshankar@fas.harvard.edu

Website: http://www.isites.harvard.edu/k77246

Office Hours: W 3-4 51 Brattle St

Sections: Th 5:30-6:30TBA

Today’s Agenda

• Go Over Syllabus–Objectives–Requirements–Readings–Topics

• What is Game Theory?• An Experiment• Next Time

Description

Game theory is the study of interdependent decision-making. In the early days of the cold war, game theory was used to analyze an emerging nuclear arms race; today, it has applications in economics, psychology, politics, the law and other fields. In this course, we will explore the “strategic way of thinking” as developed by game theorists over the past sixty years. Special attention will be paid to the move from zero-sum to nonzero-sum game theory.

Description

Students will learn the basic solution concepts of game theory -- including minimax and Nash equilibrium -- by playing and analyzing games in class, and then we will take up some game-theoretic applications in negotiation settings: the strategic use of threats, bluffs and promises. We will also study the repeated prisoner’s dilemma and investigate how cooperative behavior may emerge in a population of rational egoists.

Description

This problematic -- “the evolution of cooperation” -- extends from economics and political science to biology and artificial intelligence, and it presents a host of interesting challenges for both theoretical and applied research. Finally, we will consider the changing context for the development of game theory today, in particular, the need to achieve international cooperation on economic and environmental issues.

Objectives

The course has two main objective: to introduce students to the fundamental problems and solution concepts of noncooperative game theory; and to provide an historical perspective on its development, from the analysis of military conflicts to contemporary applications in economics and other fields. No special mathematical preparation is required.

Requirements

10% Section. Include new material.

20% Problem Sets. Due in class.30% Midterm Exam. In class: March 23. 40% Final Exam. May 11.

Requirements

10% Section. Include new material.

20% Problem Sets. Due in class.30% Midterm Exam. In class: March 23. 40% Final Exam. May 11.

Graduate Credit: 12-15 page paper, May 6.

ReadingsAxelrod, The Evolution of Cooperation (1984).Gibbons, Game Theory for Applied Economists (1992).Poundstone, Prisoner’s Dilemma (1992).Rapoport, Two-Person Game Theory (1966).Schelling, The Strategy of Conflict (1960).

Available at the Coop (and elsewhere)

Additional Readings denoted by an asterisk (*) are available via the website under “Library Research”

ReadingsREADINGS RECOMMENDED FOR FURTHER INTEREST

Binmore, Game Theory & the Social Contract, Vol II (1998).

Dutta, Strategies & Games (1999).Gintis, Game Theory Evolving (2000).Hargreaves-Heap & Varoufakis. Game Theory: A Critical

Introduction (1995).Kreps, Game Theory & Economic Modeling (1994).Raiffa, The Art & Science of Negotiation (1982).Schelling, Choice & Consequence (1984).

ReadingsREADINGS RECOMMENDED FOR FURTHER INTEREST

Binmore, Game Theory & the Social Contract, Vol II (1998).

Dutta, Strategies & Games (1999).Gintis, Game Theory Evolving (2000).Hargreaves-Heap & Varoufakis. Game Theory: A Critical

Introduction (1995).Kreps, Game Theory & Economic Modeling (1994).Raiffa, The Art & Science of Negotiation (1982).Schelling, Choice & Consequence (1984).

Academic Honesty

Harvard takes matters of academic honesty very seriously. While you may discuss assignments with your classmates and others, make sure any written material you submit is your own work. Use of old course materials, including exams and problem sets from online sources, is prohibited. You should consult the Official Register of the Harvard Extension School and the website http://www.extension.harvard.edu to familiarize yourself with the possible serious consequences of academic dishonesty .

Problem Sets

There will be 4 problem sets assigned roughly every other week, due at the beginning of class. Each problem set will be graded on a 10 point scale and count for 5% of your final grade.

Sections

Attendance at sections is mandatory, and missed sections or tardiness may reduce your section grade. Participation by all students is strongly encouraged. Sections will be especially helpful in preparing for problem sets and reviewing for exams. The quality of your section experience depends heavily on the involvement of other students. As such, fostering a supportive, cooperative environment will be essential. Part of your participation grade will be based on your contribution to the learning environment in the classroom.

WebsiteThe course website is a very useful place for you to visit: www.isites.harvard.edu/k77246.

All official course announcements (e.g., deadlines, class cancellations, exam notices, etc.) will appear on the homepage, and all assignments and answer keys will be posted there. There is also a discussion section, practice problems, additional readings, links to interesting sites, and other useful resources.

TopicsUNIT I OVERVIEW AND HISTORYUNIT II THE BASIC THEORY

March 23 MIDTERM

UNIT III THE EVOLUTION OF COOPERATIONUNIT IV THINKING ABOUT THINKING May 11 FINAL EXAM

TopicsUNIT I OVERVIEW AND

HISTORY

1/26 Introduction: What is Game Theory?2/2 Von Neumann and the Bomb.

The Science of International Strategy.2/9 The Logic of Indeterminate Situations.

7/4 HOLIDAY

TopicsUNIT II THE BASIC THEORY

2/16 Zerosum and Nonzerosum Games.

2/23 Nash Equilibrium: properties and problems.3/2 Bargaining Problems and (some) Solutions.3/9 Review

3/23 MIDTERM

TopicsUNIT III THE EVOLUTION OF COOPERATION

3/30 The Evolution of International Cooperation?Repeated Games: the Folk Theorem.

4/6 Evolutionary Games.A Tournament.

4/13 How to Promote Cooperation.Unit Review.

TopicsUNIT IV THINKING ABOUT THINKING

4/20 Playing Fair.Behavioral Game Theory.

4/27 Learning Models.Conclusions and Review.

5/4 Conclusions and Review.

5/11 FINAL EXAM

UNIT I: Overview & History

• Introduction: What is Game Theory?• Von Neumann and the Bomb• The Science of International Strategy• Logic of Indeterminate Situations

1/26

What is Game Theory?

• Games of Strategy v. Games of Chance• The Strategic Way of Thinking• An Experiment• Next Time

If we confine our study to the theory of strategy, we seriously restrict ourselves by the assumption of rational behavior – not just of intelligent behavior, but of behavior motivated by a conscious calculation of advantages, a calculation that in turn is based on an explicit and internally consistent value system (Schelling, 1960, p. 4).

What is Game Theory?

What is Game Theory?

Normative theories tell us how a rational player will behave.

Descriptive theories tell us how real people actually behave.

Prescriptive theories offer advice on how real people should behave.

What is Game Theory?

Rationality: The assumption that a player will attempt to maximize her expected payoff from playing a game.

Strategy: A complete plan of action for every possible decision in a game.

Equilibrium: A state of the game in which no player has an incentive to change her strategy.

Definitions (preliminary)

What is Game Theory?

Rationality: The assumption that a player will attempt to maximize her expected payoff from playing a game.

Strategy: A complete plan of action for every possible decision in a game.

Equilibrium: A state of the game in which no player has an incentive to change her strategy.

Definitions (preliminary)

What is Game Theory?

Rationality: The assumption that a player will attempt to maximize her expected payoff from playing a game.

Strategy: A complete plan of action for every possible decision in a game.

Equilibrium: A state of the game in which no player has an incentive to change her strategy.

Definitions (preliminary)

Rationality: choosing the best MEANS to attain given ENDS.

MEANS ENDSActions Preferences(x, y) A > B

B > A where: x = buy A A = B

y = buy B

What is Game Theory?

Rationality: choosing the best MEANS to attain given ENDS.

MEANS ENDSActions Preferences(x, y) A > B

B > A where: x = buy A A = B

y = buy B

What is Game Theory?

?

What is Game Theory?N = 1 n ¥

MONOPOLY ? PERFECT COMPETITION

Price setter ? Price taker Inefficient ? Efficient

Game theory confronts this problem at the heart of economic theory: a theory of rational behavior when people interact directly, and prices are determined endogenously.

Games of Chance

Buy Don’t Buy

(1000) (-1) (0) (0)

Player 1

Chance

You are offered a fair gamble to purchase a lottery ticket that pays $1000, if your number is drawn. The ticket costs $1.

Games of Chance

Buy Don’t Buy

(1000) (-1) (0) (0)

Player 1

Chance

You are offered a fair gamble to purchase a lottery ticket that pays $1000, if your number is drawn. The ticket costs $1.

The chance of your number being chosen is fixed by statistical laws.

Games of Strategy

Buy Don’t Buy

(1000) (-1) (0) (0)

Player 1

Player 2

Player 2 chooses the winning number.

Games of Strategy

Buy Don’t Buy

(1000,-1000) (-1,1) (0,0) (0,0)

Player 1

Player 2

Player 2 chooses the winning number.

What are Player 2’s payoffs?

• Games of strategy require at least two players. • Players choose strategies and get payoffs. Chance

is not a player!• In games of chance, uncertainty is probabilistic,

random, subject to statistical regularities.• In games of strategy, uncertainty is not random;

rather it results from the choice of another strategic actor.

• Thus, game theory is to games of strategy as probability theory is to games of chance.

Games of Strategy

• Games of strategy require at least two players. • Players choose strategies and get payoffs. Chance

is not a player!• In games of chance, uncertainty is probabilistic,

random, subject to statistical regularities.• In games of strategy, uncertainty is not random;

rather it results from the choice of another strategic actor.

• Thus, game theory is to games of strategy as probability theory is to games of chance.

Games of Strategy

• Games of strategy require at least two players. • Players choose strategies and get payoffs. Chance

is not a player!• In games of chance, uncertainty is probabilistic,

random, subject to statistical regularities.• In games of strategy, uncertainty is not random;

rather it results from the choice of another strategic actor.

• Thus, game theory is to games of strategy as probability theory is to games of chance.

Games of Strategy

Games of Chance Games of StrategyExamples Roulette Chess, PokerPlayers 1 > 2Uncertainty Random Strategic (non-random)

Probability theory Game theory

(Statistics)

• Thus, game theory is to games of strategy as probability theory is to games of chance.

Games of Strategy

The Strategic Way of Thinking

The parametrically rational actor treats his environment as a constant, whereas the strategically rational actor takes account of the fact that the environment is made up of other actors and that he is part of their environment, and that they know this, etc. In a community of parametrically rational actors each will believe that he is the only one whose behavior is variable, and that all others are parameters for his decision problem (Elster, 1979, p. 18).

The Strategic Way of Thinking

In the strategic or game-theoretic mode of interaction, each actor has to take account of the intentions of all other actors, including the fact that their intentions are based upon their expectations concerning his own (Elster, 1979, p. 18).

An ExperimentA) Smallest Value of X

7 6 5 4 3 2 1Your 7 1.30 1.10 0.90 0.70 0.50 0.30 0.10Choice 6 - 1.20 1.00 0.80 0.60 0.40 0.20of 5 - - 1.10 0.90 0.70 0.50 0.30X 4 - - - 1.00 0.80 0.60 0.40

3 - - - - 0.90 0.70 0.50 2 - - - - - 0.80 0.60 1 - - - - - - 0.70

Your Payoff = 0.10(Your Choice of X) - 0.20(Your Choice of X - Smallest X) + 0.60

(Source: Van Huyck, Battalio and Beil, 1990)

An ExperimentA) Smallest Value of X

7 6 5 4 3 2 1Your 7 1.30 1.10 0.90 0.70 0.50 0.30 0.10Choice 6 - 1.20 1.00 0.80 0.60 0.40 0.20of 5 - - 1.10 0.90 0.70 0.50 0.30X 4 - - - 1.00 0.80 0.60 0.40

3 - - - - 0.90 0.70 0.50 2 - - - - - 0.80 0.60 1 - - - - - - 0.70

7 is the efficient choice

An ExperimentA) Smallest Value of X

7 6 5 4 3 2 1Your 7 1.30 1.10 0.90 0.70 0.50 0.30 0.10Choice 6 - 1.20 1.00 0.80 0.60 0.40 0.20of 5 - - 1.10 0.90 0.70 0.50 0.30X 4 - - - 1.00 0.80 0.60 0.40

3 - - - - 0.90 0.70 0.50 2 - - - - - 0.80 0.60 1 - - - - - - 0.70

1 is the secure (or prudent) choice

An ExperimentA) Smallest Value of X

7 6 5 4 3 2 1Your 7 1.30 1.10 0.90 0.70 0.50 0.30 0.10Choice 6 - 1.20 1.00 0.80 0.60 0.40 0.20of 5 - - 1.10 0.90 0.70 0.50 0.30X 4 - - - 1.00 0.80 0.60 0.40

3 - - - - 0.90 0.70 0.50 2 - - - - - 0.80 0.60 1 - - - - - - 0.70

Multiple equilibria COORDINATION PROBLEM

An Experiment

What happened when we played the game?

What would happen if communication were permitted?

Is there a rational way to play?

Next Time

2/2 Von Neumann and the Bomb

Poundstone: 1-166.Schelling, Strategy and Conflict: 3-52; 207-254Hayward, Military Decision & Game Theory: 365-385 *