Game theory is a mathematical approach to modeling strategic interactions between rational decision-makers. It assumes humans seek the best outcomes and makes predictions based on payoff matrices showing players' rewards for different strategy combinations. Common applications include economics, politics, and analyzing conflict and cooperation situations like the Prisoner's Dilemma. Game theory also studies concepts like Nash equilibrium, mixed strategies, and evolutionary stable strategies.
This document provides an overview of game theory. It defines game theory as the study of how people interact and make decisions in strategic situations, using mathematical models. It discusses the history and key concepts of game theory, including players, strategies, payoffs, assumptions of rationality and perfect information. It provides examples of zero-sum and non-zero-sum games like the Prisoner's Dilemma. The document also outlines the key elements of a game and different types of game theory, and discusses applications in economics, computer science, military strategy, biology and other fields.
This document provides an overview of game theory. It defines game theory as the study of how people interact and make decisions strategically, taking into account that each person's actions impact others. It discusses the history and key concepts of game theory, including players, strategies, payoffs, assumptions of rationality and perfect information. It provides examples of zero-sum and non-zero-sum games like the Prisoner's Dilemma. The document is intended to introduce game theory and its basic elements.
Does any player have a dominated strategy?
If there is a dominated strategy, eliminate it.
If there is no dominant or dominated strategy, the game is unsolved by dominance. We need to look at other solution concepts like Nash equilibrium.
This document provides an overview of game theory, including:
- Defining game theory as a way to study strategic decision-making involving multiple participants with conflicting goals.
- The major assumptions of game theory include players having different objectives, making decisions simultaneously, and knowing potential payoffs.
- Common types of games are cooperative/non-cooperative, zero-sum/non-zero-sum, and simultaneous/sequential games.
- Popular examples used in game theory include the Prisoner's Dilemma and Chicken games, which demonstrate outcomes like Nash equilibrium.
- Game theory has applications in economics, politics, biology, and other fields for modeling interactions and predicting outcomes.
Game theory is the study of strategic decision making. It involves analyzing interactions between players where the outcome for each player depends on the actions of all players. Key concepts in game theory include Nash equilibrium, where each player's strategy is the best response to the other players' strategies, and Prisoner's Dilemma, where the non-cooperative equilibrium results in a worse outcome for both players than if they had cooperated. Game theory is applied in economics, political science, biology, and many other fields to model strategic interactions.
This document provides an overview of game theory and its key concepts. It defines game theory, agents, multi-agent systems, and the basic elements of games. It then explains concepts like pure and mixed strategies, Nash equilibrium, different types of games, and applications of game theory. Game theory is presented as a mathematical study of strategic decision-making between interdependent parties.
Game theory is the study of interactive decision making between multiple agents where the payoff for each agent depends on the choices of the other agents. The document discusses the history and key concepts of game theory including normal and extensive forms, symmetric and asymmetric games, cooperative and non-cooperative games, zero-sum and non-zero-sum games, and Nash equilibrium. Nash equilibrium refers to a set of strategies where no player can benefit by changing their strategy given the strategies of other players.
Game theory is the analysis of strategic decision making between intelligent rational players. It uses models and solution concepts to analyze interactions in fields like economics, politics, and biology. Important concepts in game theory include Nash equilibrium, where each player's strategy is optimal given the other players' strategies, and mixed strategies, which involve randomizing between pure strategies. Game theory has applications in many domains and seeks to predict outcomes of interactions between decision makers.
Game theory seeks to analyze competing situations that arise from conflicts of interest. It examines scenarios of conflict to identify optimal strategies for decision makers. Game theory assumes importance from a managerial perspective, as businesses compete for market share. The theory can help determine rational behaviors in competitive situations where outcomes depend on interactions between decision makers and competitors. It provides insights to help businesses convert weaknesses and threats into opportunities and strengths to maximize profits.
This document provides an overview of game theory, including its history, basic concepts, types of strategies and equilibria, different types of games, and applications. It defines game theory as the mathematical analysis of conflict situations to determine optimal strategies. Key concepts explained include Nash equilibrium, mixed strategies, zero-sum games, repeated games, and sequential vs. simultaneous games. Applications of game theory discussed include economics, politics, biology, and artificial intelligence.
Game theory is a branch of applied mathematics that analyzes strategic interactions between agents. It includes concepts like Nash equilibrium, mixed strategies, and coordination games. Game theory is used in economics, political science, biology, and other social sciences to model how individuals make decisions in strategic situations where outcomes depend on the decisions of others.
Lecture OverviewSolving the prisoners dilemmaInstrumental r.docxSHIVA101531
油
Lecture Overview
Solving the prisoners dilemma
Instrumental rationality
Morality & norms
Repeated games
Three ways to solve the prisoners dilemma
Sequential games
Backward induction
Subgame perfect Nash equilibrium
Common knowledge of rationality
Mixed strategies
Game theory: underlying assumptions
Remember:
Homo economicus: instrumental rationality and preferences
Common knowledge of rationality and consistent alignment of believes: given the same information individuals arrive at the same decisions
Individuals know the rules of the game which are exogenously given and independent of individuals choices
We will look at these one by one, analysing alternative assumptions.
We will use the prisoners dilemma as example.
Why?
Coordination game with conflict
Arguably it describes many social situations, e.g. the free rider problem:
Voting
Trade union affiliation
Wage cuts to increase profit
Domestic work
Prisoners dilemma
The homo economicus maximises his/her utility.
In a prisoners dilemma the dominant strategy is to confess (defect).
Fallacy of compositions: what is individually rational is neither Pareto optimal not socially rational.
But do people really defect?
Kants categorical imperative: not the outcome but the act is crucial (morality)
Altruism: blood donation
Social norms: forest people hunting in the Congo (Turnbull 1963)
Instrumental rationality
Gauthier: it is instrumentally rational to cooperate rather than to defect
Assume there are two sorts of maximisers in the economy: straight maximisers (SM) and constrained maximisers (CM); SMs defect, CMs cooperate with other CMs:
E(return from CM) = p*(-1)+(1-p)*(-3)
E(return from SM) = -3
For any p>0 the CM
strategy is better than
the SM one.
Instrumental rationality
Tit-for-tat
Unsurprisingly (maybe), in a repeated Prisoners dilemma the best strategy is not to defect but to adopt a tit-for-tat strategy.
In the 1980s, Robert Axelrod invited professional game theorists to enter strategies into a tournament of a repeated game (200 times).
The winning strategy was tit-for-tat entered by Anatol Rapaport:
Start off with cooperation
If opponent defects punish him/her by defecting
If opponent comes back to cooperation forgive them and go back to cooperation
Overall, forgiving and cooperative strategies did better.
Repeated games & reputation
A tit-for-tat strategy can only be played in repeated games.
The folk theorem states that in an infinitely repeated game (or given uncertainty to the end of the game) any strategy with a feasible payoff can be an equilibrium.
This is important for social interaction: the prisoners dilemma can be overcome without (!) external authority.
Players enforce compliance (cooperate rather than defect) through punishment.
The loss of future returns deters players from defecting.
The surprising thing about Axelrods tournament was that the tit-for-tat strategy won in a finite (and defined) repeated game ...
Game theory is a strategic decision-making process that models interactions between two or more players. It is commonly used in economics to analyze industries and competition between firms. Key concepts in game theory include games, players, strategies, payoffs, information sets, equilibriums, assumptions of rationality and payoff maximization. Common solution techniques include backwards induction, Nash equilibriums, mixed strategies, and minimax strategies. Examples discussed include prisoner's dilemmas, zero-sum games, and dominance.
Game theory is a strategic decision-making process that models interactions between two or more players. It is commonly used in economics to analyze industries and competition between firms. Key concepts in game theory include games, players, strategies, payoffs, information sets, equilibriums, assumptions of rationality and payoff maximization. Common applications discussed are the prisoner's dilemma, zero-sum games, dominant and dominated strategies, Nash equilibriums, mixed strategies, and minimax strategies.
This document provides an introduction and overview of game theory. It discusses how game theory analyzes situations where players' decisions are interdependent and they must consider other players' strategies. Game theory was originally developed to study games but is now used in many fields to model strategic decision-making. The document outlines some basic game theory concepts and assumptions. It also notes there are different theories within game theory applicable to different types of games.
This presentation is an attempt to introduce Game Theory in one session. It's suitable for undergraduates. In practice, it's best used as a taster since only a portion of the material can be covered in an hour - topics can be chosen according to the interests of the class.
The main reference source used was 'Games, Theory and Applications' by L.C.Thomas. Further notes available at: http://bit.ly/nW6ULD
Game theory is the formal study of strategic decision making between interdependent agents. It provides a framework to model, analyze, and understand strategic situations. The document introduces key concepts in game theory including the prisoner's dilemma, dominance, Nash equilibrium, mixed strategies, extensive games, and zero-sum games. It also discusses the history and applications of game theory, particularly in economics, politics, and information systems.
Game theory is the formal study of strategic decision-making between interdependent agents. The document provides an overview of game theory, including its history, key concepts such as the Nash equilibrium, applications in economics and information systems, and different types of games. It defines games formally and discusses the differences between cooperative and noncooperative game theory, with the latter explicitly modeling the strategic decision process.
OR PPT 280322 maximin final - nikhil tiwari.pptxVivekSaurabh7
油
Maximin and Minimax strategies are approaches used in game theory to determine the optimal strategy for players. Maximin selects the strategy that maximizes the minimum possible payoff, while Minimax selects the strategy that minimizes the maximum possible loss. These strategies are applied in zero-sum games under the assumptions of rational opponents. The strategies can be modeled using decision trees and algorithms like Minimax to analyze games like Tic Tac Toe and determine the best move.
This document provides an introduction to decision making using game theory. It defines game theory as attempting to mathematically model strategic situations where an individual's success depends on the choices of others. It outlines the basic constituents of games including players, actions/strategies, rules, types of games, and branches of game theory. Game theory can be applied to management areas like industrial organization strategies, corporate finance, and mechanism/auction design.
The document provides an overview of game theory, including its basic terminology and solution methods for different types of games. It discusses pure and mixed strategy games, zero-sum and non-zero sum games, and approaches like Nash equilibrium. Limitations of game theory are noted, such as its assumptions of complete information and risk averse players not reflecting real world situations.
This document discusses applications of game theory in computer science, specifically in networking and algorithm analysis. It introduces fundamental game theory concepts like the Nash equilibrium. It then explores how game theory can be used to model network security as a stochastic game between a hacker and security team, allowing analysis of optimal strategies. It also explains Yao's minimax principle, which uses game theory to relate the complexities of deterministic and randomized algorithms by modeling them as players in a zero-sum game. By representing problems in game theoretic terms, complex issues can be analyzed to find solutions.
1. The document provides a brief introduction to the basics of game theory, covering fundamental concepts such as normal form games, dominant strategies, and Nash equilibrium.
2. It uses the prisoners' dilemma game and a Cournot duopoly game to illustrate the concept of a normal form game and dominant strategies. Both games have a unique Nash equilibrium where both players defect.
3. Nash equilibrium is defined as a profile of strategies where each player's strategy is a best response to the other players' strategies. An example advertising game is presented to illustrate the concept of Nash equilibrium.
Game theory is the analysis of strategic decision making between intelligent rational players. It uses models and solution concepts to analyze interactions in fields like economics, politics, and biology. Important concepts in game theory include Nash equilibrium, where each player's strategy is optimal given the other players' strategies, and mixed strategies, which involve randomizing between pure strategies. Game theory has applications in many domains and seeks to predict outcomes of interactions between decision makers.
Game theory seeks to analyze competing situations that arise from conflicts of interest. It examines scenarios of conflict to identify optimal strategies for decision makers. Game theory assumes importance from a managerial perspective, as businesses compete for market share. The theory can help determine rational behaviors in competitive situations where outcomes depend on interactions between decision makers and competitors. It provides insights to help businesses convert weaknesses and threats into opportunities and strengths to maximize profits.
This document provides an overview of game theory, including its history, basic concepts, types of strategies and equilibria, different types of games, and applications. It defines game theory as the mathematical analysis of conflict situations to determine optimal strategies. Key concepts explained include Nash equilibrium, mixed strategies, zero-sum games, repeated games, and sequential vs. simultaneous games. Applications of game theory discussed include economics, politics, biology, and artificial intelligence.
Game theory is a branch of applied mathematics that analyzes strategic interactions between agents. It includes concepts like Nash equilibrium, mixed strategies, and coordination games. Game theory is used in economics, political science, biology, and other social sciences to model how individuals make decisions in strategic situations where outcomes depend on the decisions of others.
Lecture OverviewSolving the prisoners dilemmaInstrumental r.docxSHIVA101531
油
Lecture Overview
Solving the prisoners dilemma
Instrumental rationality
Morality & norms
Repeated games
Three ways to solve the prisoners dilemma
Sequential games
Backward induction
Subgame perfect Nash equilibrium
Common knowledge of rationality
Mixed strategies
Game theory: underlying assumptions
Remember:
Homo economicus: instrumental rationality and preferences
Common knowledge of rationality and consistent alignment of believes: given the same information individuals arrive at the same decisions
Individuals know the rules of the game which are exogenously given and independent of individuals choices
We will look at these one by one, analysing alternative assumptions.
We will use the prisoners dilemma as example.
Why?
Coordination game with conflict
Arguably it describes many social situations, e.g. the free rider problem:
Voting
Trade union affiliation
Wage cuts to increase profit
Domestic work
Prisoners dilemma
The homo economicus maximises his/her utility.
In a prisoners dilemma the dominant strategy is to confess (defect).
Fallacy of compositions: what is individually rational is neither Pareto optimal not socially rational.
But do people really defect?
Kants categorical imperative: not the outcome but the act is crucial (morality)
Altruism: blood donation
Social norms: forest people hunting in the Congo (Turnbull 1963)
Instrumental rationality
Gauthier: it is instrumentally rational to cooperate rather than to defect
Assume there are two sorts of maximisers in the economy: straight maximisers (SM) and constrained maximisers (CM); SMs defect, CMs cooperate with other CMs:
E(return from CM) = p*(-1)+(1-p)*(-3)
E(return from SM) = -3
For any p>0 the CM
strategy is better than
the SM one.
Instrumental rationality
Tit-for-tat
Unsurprisingly (maybe), in a repeated Prisoners dilemma the best strategy is not to defect but to adopt a tit-for-tat strategy.
In the 1980s, Robert Axelrod invited professional game theorists to enter strategies into a tournament of a repeated game (200 times).
The winning strategy was tit-for-tat entered by Anatol Rapaport:
Start off with cooperation
If opponent defects punish him/her by defecting
If opponent comes back to cooperation forgive them and go back to cooperation
Overall, forgiving and cooperative strategies did better.
Repeated games & reputation
A tit-for-tat strategy can only be played in repeated games.
The folk theorem states that in an infinitely repeated game (or given uncertainty to the end of the game) any strategy with a feasible payoff can be an equilibrium.
This is important for social interaction: the prisoners dilemma can be overcome without (!) external authority.
Players enforce compliance (cooperate rather than defect) through punishment.
The loss of future returns deters players from defecting.
The surprising thing about Axelrods tournament was that the tit-for-tat strategy won in a finite (and defined) repeated game ...
Game theory is a strategic decision-making process that models interactions between two or more players. It is commonly used in economics to analyze industries and competition between firms. Key concepts in game theory include games, players, strategies, payoffs, information sets, equilibriums, assumptions of rationality and payoff maximization. Common solution techniques include backwards induction, Nash equilibriums, mixed strategies, and minimax strategies. Examples discussed include prisoner's dilemmas, zero-sum games, and dominance.
Game theory is a strategic decision-making process that models interactions between two or more players. It is commonly used in economics to analyze industries and competition between firms. Key concepts in game theory include games, players, strategies, payoffs, information sets, equilibriums, assumptions of rationality and payoff maximization. Common applications discussed are the prisoner's dilemma, zero-sum games, dominant and dominated strategies, Nash equilibriums, mixed strategies, and minimax strategies.
This document provides an introduction and overview of game theory. It discusses how game theory analyzes situations where players' decisions are interdependent and they must consider other players' strategies. Game theory was originally developed to study games but is now used in many fields to model strategic decision-making. The document outlines some basic game theory concepts and assumptions. It also notes there are different theories within game theory applicable to different types of games.
This presentation is an attempt to introduce Game Theory in one session. It's suitable for undergraduates. In practice, it's best used as a taster since only a portion of the material can be covered in an hour - topics can be chosen according to the interests of the class.
The main reference source used was 'Games, Theory and Applications' by L.C.Thomas. Further notes available at: http://bit.ly/nW6ULD
Game theory is the formal study of strategic decision making between interdependent agents. It provides a framework to model, analyze, and understand strategic situations. The document introduces key concepts in game theory including the prisoner's dilemma, dominance, Nash equilibrium, mixed strategies, extensive games, and zero-sum games. It also discusses the history and applications of game theory, particularly in economics, politics, and information systems.
Game theory is the formal study of strategic decision-making between interdependent agents. The document provides an overview of game theory, including its history, key concepts such as the Nash equilibrium, applications in economics and information systems, and different types of games. It defines games formally and discusses the differences between cooperative and noncooperative game theory, with the latter explicitly modeling the strategic decision process.
OR PPT 280322 maximin final - nikhil tiwari.pptxVivekSaurabh7
油
Maximin and Minimax strategies are approaches used in game theory to determine the optimal strategy for players. Maximin selects the strategy that maximizes the minimum possible payoff, while Minimax selects the strategy that minimizes the maximum possible loss. These strategies are applied in zero-sum games under the assumptions of rational opponents. The strategies can be modeled using decision trees and algorithms like Minimax to analyze games like Tic Tac Toe and determine the best move.
This document provides an introduction to decision making using game theory. It defines game theory as attempting to mathematically model strategic situations where an individual's success depends on the choices of others. It outlines the basic constituents of games including players, actions/strategies, rules, types of games, and branches of game theory. Game theory can be applied to management areas like industrial organization strategies, corporate finance, and mechanism/auction design.
The document provides an overview of game theory, including its basic terminology and solution methods for different types of games. It discusses pure and mixed strategy games, zero-sum and non-zero sum games, and approaches like Nash equilibrium. Limitations of game theory are noted, such as its assumptions of complete information and risk averse players not reflecting real world situations.
This document discusses applications of game theory in computer science, specifically in networking and algorithm analysis. It introduces fundamental game theory concepts like the Nash equilibrium. It then explores how game theory can be used to model network security as a stochastic game between a hacker and security team, allowing analysis of optimal strategies. It also explains Yao's minimax principle, which uses game theory to relate the complexities of deterministic and randomized algorithms by modeling them as players in a zero-sum game. By representing problems in game theoretic terms, complex issues can be analyzed to find solutions.
1. The document provides a brief introduction to the basics of game theory, covering fundamental concepts such as normal form games, dominant strategies, and Nash equilibrium.
2. It uses the prisoners' dilemma game and a Cournot duopoly game to illustrate the concept of a normal form game and dominant strategies. Both games have a unique Nash equilibrium where both players defect.
3. Nash equilibrium is defined as a profile of strategies where each player's strategy is a best response to the other players' strategies. An example advertising game is presented to illustrate the concept of Nash equilibrium.
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Aggregate planning involves determining a company's production capacity needs. Capacity planning establishes the optimal output rate for facilities and involves strategic decisions about capital investments. Measuring capacity depends on the type of business and inputs or outputs. Effective capacity is the maximum output under normal conditions, while design capacity is the maximum under ideal conditions. Capacity utilization compares actual output to capacity to measure effectiveness. When determining optimal capacity levels, companies consider economies and diseconomies of scale. Timing capacity changes and maintaining flexibility are also important planning decisions.
A glimpse into the world of Caddlance! Explore our portfolio featuring captivating 3D renderings, detailed BIM models, and inspiring architectural designs. Let's build the future, together. #Architecture #3D #BIM #Caddlance
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Security requirements are often treated as generic lists of features, neglecting system-specific needs and the attacker's perspective. A systematic approach to security requirements engineering is crucial to avoid this problem.
Requirements engineering defects can cost 10 to 200 times more to correct once the system is operational. Software development takes place in a dynamic environment, causing requirements to constantly change.
Ktor - Definizioni di Path, Integrazioni, Plugin e build fino al rilascioinfogdgmi
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Tra i vari framework backend basati sulla JVM, uno in particolare, con il passare del tempo, ha saputo ritagliarsi il suo spazio: era Ktor (figlio di Kmer).
In questo talk faremo un tour di Ktor,
dalla sua parte backend: Definizioni di Path, Integrazioni, Plugin e build fino al rilascio (e qualche chicca),
fino alla sua controparte client e qualche sua integrazione
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Production Planning and Control : Importance, Objectives and Functions . Inventory Management - Meaning, Types , Objectives, Selective Inventory Control : ABC Analysis
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Software is often designed with security as an afterthought, leading to vulnerabilities that can be exploited by attackers. This has become a critical issue as our reliance on software continues to grow.
Increasing number and sophistication of attacks (CERT vulnerability reports rising).
Software security is the practice of protecting applications from unauthorized access, modification, and destruction.
Secure software development practices.
Executives (E)
Project Managers (M)
Technical Leaders (L)
2. General approach
Brief History of Game Theory
Payoff Matrix
Types of Games
Basic Strategies
Evolutionary Concepts
Limitations and Problems
3. Brief History of Game Theory
1913 - E. Zermelo provides the first theorem of
game theory; asserts that chess is strictly
determined
1928 - John von Neumann proves the minimax
theorem
1944 - John von Neumann & Oskar
Morgenstern write "Theory of Games and
Economic Behavior
1950-1953 - John Nash describes Nash
equilibrium
4. Rationality
Assumptions:
humans are rational beings
humans always seek the best alternative
in a set of possible choices
Why assume rationality?
narrow down the range of possibilities
predictability
5. Utility Theory
Utility Theory based on:
rationality
maximization of utility
may not be a linear function of income or
wealth
It is a quantification of a person's preferences
with respect to certain objects.
6. What is Game Theory?
Game theory is a study of how to
mathematically determine the best strategy for
given conditions in order to optimize the
outcome
7. Game Theory
Finding acceptable, if not optimal,
strategies in conflict situations.
Abstraction of real complex situation
Game theory is highly mathematical
Game theory assumes all human
interactions can be understood and
navigated by presumptions.
8. Why is game theory important?
All intelligent beings make decisions all the time.
AII needs to perform these tasks as a result.
Helps us to analyze situations more rationally and
formulate an acceptable alternative with respect to
circumstance.
Useful in modeling strategic decision-making
Games against opponents
Games against "nature
Provides structured insight into the value of
information
9. Types of Games
Sequential vs. Simultaneous moves
Single Play vs. Iterated
Zero vs. non-zero sum
Perfect vs. Imperfect information
Cooperative vs. conflict
10. Zero-Sum Games
The sum of the payoffs remains constant
during the course of the game.
Two sides in conflict
Being well informed always helps a
player
11. Non-zero Sum Game
The sum of payoffs is not constant during the
course of game play.
Players may co-operate or compete
Being well informed may harm a player.
12. Games of Perfect Information
The information concerning an opponents
move is well known in advance.
All sequential move games are of this type.
13. Imperfect Information
Partial or no information concerning the
opponent is given in advance to the players
decision.
Imperfect information may be diminished
over time if the same game with the same
opponent is to be repeated.
15. Matrix Notation
(Column) Player II
Strategy A Strategy B
(Row) Player I
Strategy A (P1, P2) (P1, P2)
Strategy B (P1, P2) (P1, P2)
Notes: Player I's strategy A may be different from Player II's.
P2 can be omitted if zero-sum game
16. Prisoners Dilemma &
Other famous games
A sample of other games:
Marriage
Disarmament (my generals are
more irrational than yours)
17. Prisoners Dilemma
Notes: Higher payoffs (longer sentences) are bad.
Non-cooperative equilibrium Joint maximum
Institutionalized solutions (a la criminal organizations, KSM)
NCE
Jt. max.
18. Games of Conflict
Two sides competing against each other
Usually caused by complete lack of
information about the opponent or the game
Characteristic of zero-sum games
19. Games of Co-operation
Players may improve payoff through
communicating
forming binding coalitions & agreements
do not apply to zero-sum games
Prisoners Dilemma
with Cooperation
20. Prisoners Dilemma with Iteration
Infinite number of iterations
Fear of retaliation
Fixed number of iteration
Domino effect
21. Basic Strategies
1. Plan ahead and look back
2. Use a dominating strategy if possible
3. Eliminate any dominated strategies
4. Look for any equilibrium
5. Mix up the strategies
25. Look for any equilibrium
Dominating Equilibrium
Minimax Equilibrium
Nash Equilibrium
26. Maximin & Minimax Equilibrium
Minimax - to minimize the maximum loss
(defensive)
Maximin - to maximize the minimum gain
(offensive)
Minimax = Maximin
28. Definition: Nash Equilibrium
If there is a set of strategies with the property
that no player can benefit by changing her
strategy while the other players keep their
strategies unchanged, then that set of
strategies and the corresponding payoffs
constitute the Nash Equilibrium.
Source: http://www.lebow.drexel.edu/economics/mccain/game/game.html
32. Time for "real-life" decision making
Holmes & Moriarity in "The Final Problem"
What would you do
If you were Holmes?
If you were Moriarity?
Possibly interesting digressions?
Why was Moriarity so evil?
What really happened?
What do we mean by reality?
What changed the reality?
34. Mixed Strategy Solution
Value in
Safe
Probability
of being
Guarded
Expected
Loss
Safe 1 10,000
$ 1 / 11 9,091
$
Safe 2 100,000
$ 10 / 11 9,091
$
Both 110,000
$
35. The Payoff Matrix
for Holmes & Moriarity
P
l
a
y
e
r
#
1
Player #2
Strategy #1 Strategy #2
Strategy #1
Strategy #2
Payoff (1,1) Payoff (1,2)
Payoff (2,1) Payoff (2,2)
36. Where is game theory
currently used?
Ecology
Networks
Economics
37. Limitations & Problems
Assumes players always maximize their
outcomes
Some outcomes are difficult to provide a
utility for
Not all of the payoffs can be quantified
Not applicable to all problems
38. Summary
What is game theory?
Abstraction modeling multi-person interactions
How is game theory applied?
Payoff matrix contains each persons utilities for
various strategies
Who uses game theory?
Economists, Ecologists, Network people,...
How is this related to AI?
Provides a method to simulate a thinking agent
39. Sources
Much more available on the web.
These slides (with changes and additions) adapted
from:
http://pages.cpsc.ucalgary.ca/~jacob/Courses/Winter2000/CPSC533/Pages/i
ndex.html
Three interesting classics:
John von Neumann & Oskar Morgenstern, Theory of
Games & Economic Behavior (Princeton, 1944).
John McDonald, Strategy in Poker, Business & War
(Norton, 1950)
Oskar Morgenstern, "The Theory of Games," Scientific
American, May 1949; translated as "Theorie des Spiels,"
Die Amerikanische Rundschau, August 1949.
#4: Based on the assumption that human beings are absolutely rational in their economic choices. Specifically, the assumption is that each person maximizes her or his rewards -- profits, incomes, or subjective benefits -- in the circumstances that she or he faces. This hypothesis serves a double purpose in the study of the allocation of resources. First, it narrows the range of possibilities somewhat. Absolutely rational behavior is more predictable than irrational behavior. Second, it provides a criterion for evaluation of the efficiency of an economic system. If the system leads to a reduction in the rewards coming to some people, without producing more than compensating rewards to others (costs greater than benefits, broadly) then something is wrong. Pollution, the overexploitation of fisheries, and inadequate resources committed to research can all be examples of this.
Source:http://www.lebow.drexel.edu/economics/mccain/game/game.html
#5: Few people would risk a sure gain of $1,000,000 for an even chance of gaining $10,000,000, for example. In fact, many decisions people make, such as buying insurance policies, playing lottery games, and gambling in a casino, indicate that they are not maximizing their average profits. Game theory does not attempt to indicate what a player's goal should be; instead, it shows the player how to attain his goal, whatever it may be.
Von Neumann and Morgenstern understood this distinction, and so to accommodate all players, whatever their goals, they constructed a theory of utility. They began by listing certain axioms that they felt all "rational" decision makers would follow (for example, if a person likes tea better than milk, and milk better than coffee, then that person should like tea better than coffee). They then proved that for such rational decision makers it was possible to define a utility function that would reflect an individual's preferences; basically, a utility function assigns to each of a player's
alternatives a number that conveys the relative attractiveness of that alternative.
Maximizing someone's utility automatically determines his most preferred option. In recent years, however, some doubt has been raised about whether people actually behave in accordance with these rational rules.
Source: http://search.britannica.com/bcom/eb/article/5/0,5716,117275+6,00.html
Values assigned to alternatives is based on the relative attractiveness to an individual.
#6: game theory focuses on how groups of people interact. Game theory focuses on how players in economic games behave when, to reach their goals, they have to predict how their opponents will react to their moves.
CONCLUSION:
As a conclusion Game theory is the study of competitive interaction; it analyzes possible outcomes in situations where people are trying to score points off each other, whether in bridge, politics of war. You do this by trying to anticipate the reaction of your competitor to your next move and then factoring that reaction into your actual decision. It teaches people to think several moves ahead. From now on , Whoever it was who said it doesnt matter if you win or lose but how you play the game, missed the point. It matters very much. According to game theory, its how you play the game that usually determines whether you win or lose.
Source:http://www.ug.bcc.bilkent.edu.tr/~zyilmaz/proposal.html
#7: It is highly mathematical in order to emulated human value judgement (mental rules, fuzzy input of good or bad)
ex. Chess play
#8: WHY GAME THEORY IS IMPORTANT?
Game theory is both easy and excruciatingly difficult. People use it all the time, average people, in their daily lives. It comes into play in mundane deals like buying a car, where a certain skill in haggling is required. The buyers offer is usually formulated on the basis of what he or she presumes the seller will take. The seller is guided by a presumption about how high the buyer will go. The outcome of this negotiation could be totally positive (if the deal satisfies both parties), totally negative (if it falls through), or positive for one party and less so for the other (depending on how much is paid.)
It is used to describe any relationship and interaction, economic, social or political. And its useful in creating strategies for negotiators. It can help you win, and that is why companies and governments hire game theorists to write strategies against other players in whatever game theyre in. Mathematics and statistics are the tools they use. For example, during the Cold War the Pentagon became interested in game theory to help develop its nuclear strategy, and with some success.
You dont make a move in chess without first trying to figure out how your opponent will react to it. Game theory assumes that all-human interactions, personal, institutional, economic, can be understood and navigated by presumptions similar to those of the chess player.
Source:http://www.ug.bcc.bilkent.edu.tr/~zyilmaz/proposal.html
#10:
In zero-sum games it never helps a player to give an adversary information, and it never harms a player to learn an opponent's strategy in advance. These rules do not necessarily hold true for nonzero-sum games, however.
Source: http://search.britannica.com/bcom/eb/article/5/0,5716,117275+6,00.html
#11: Nonzero-sum game includes all games which are not constant-sum. In non-zero-sum game, the sum of the payoffs are not the same for all outcomes.
Nonzero-sum games are mixed motive games. The interests of the players are neither strictly coincident nor strictly opposed. They generate intrapersonal and interpersonal conflicts. They are not always completely soluble but they provide insights into important areas of interdependent choice. In these games, one player's losses do not always equal another player's gains.
Some nonzero-sum games are positive sum and some are negative sum:
Negative sum games are competitive, but nobody really wins, rather, everybody loses. For example, a war or a strike.
Positive sum games are cooperative, all players have one goal that they contribute together as in an educational game. For example, school newspapers or plays, building blocks, or a science exhibit.
One major example of a two-person nonzero-sum game is the prisoner's dilemma. It is a non cooperative game because the players can not communicate their intentions. (See topic 'Automata & Games Theory')
Source: http://artsci-ccwin.concordia.ca/edtech/ETEC606/conceptprinciples.html
A player may want his opponent to be well-informed. In a labour-management dispute, for example, if the labour union is prepared for a strike, it behooves it to inform management and thereby possibly achieve its goal without a long, costly conflict. In this example, management is not harmed by the advance information (it, too, benefits by avoiding the costly strike), but in other nonzero-sum games a player can be at a disadvantage if he knows his opponent's strategy. A blackmailer, for example, benefits only if he informs his victim that he will harm the victim unless his terms are met. If he does not give this information to the intended victim, the blackmailer can still do damage but he has no reason to. Thus, knowledge of the blackmailer's strategy works to the victim's disadvantage.
Source: http://search.britannica.com/bcom/eb/article/5/0,5716,117275+6,00.html
#12: A class of Game in which players move alternately and each player is completely informed of previous moves. Finite, Zero-Sum, two-player Games with perfect information (including checkers and chess) have a Saddle Point, and therefore one or more optimal strategies. However, the optimal strategy may be so difficult to compute as to be effectively impossible to determine (as in the game of Chess).
Source:http://mathworld.wolfram.com/PerfectInformation.html
#20: It might seem that the paradox inherent in the prisoners' dilemma could be resolved if the game were played repeatedly. Players would learn that they do best when both act unselfishly and cooperate; if one player failed to cooperate in one game, the other player could retaliate by not cooperating in the next game and both would lose until they began to cooperate again. When the game is repeated a fixed number of times, however, this argument fails. According to the argument, when the two shopkeepers described above set up their stores at a 10-day county fair, each should maintain a high price, knowing that if he does not, his competitor will retaliate the next day. On the 10th day, however, each shopkeeper realizes that his competitor can no longer retaliate (the fair will be closed so there is no next day); therefore each shopkeeper should lower his price on the last day. But if each shopkeeper knows that his rival will lower the price on the 10th day, he has no incentive to maintain the high price on the
ninth day. Continuing this reasoning, one concludes that "rational" shopkeepers will have a price war every day. It is only when the game is played repeatedly and neither player knows when the sequence will end that the cooperative strategy succeeds.
Source:http://search.britannica.com/bcom/eb/article/5/0,5716,117275+6,00.html
Lead to ESS.
#21: 1. Each player need to figure out the other players future responses and use them in calculating his/her best move. In AI sense, this involves the evaluation of all possible outcomes for all possible actions. (Charlie Brown Story)
2. Dominating strategy: A dominating strategy occurs if there exists a action whose associated outcome is always favorable regardless what action the other player makes. Ex. Football game again
3. Dominated strategy: A dominated strategy occurs if there exists an action whose associated outcome is always not in favor of the player regardless what action the other player makes. Ex. Football game again.
Give a example where dominating strategy doesnt always associates with a dominated strategy.
#28: a unique outcome that satisfied conditions:
(1) the solution must be independent of the choice of utility function (if a player prefers x to y and one function assigns x a utility of 10 and y a utility of 1 while a second function assigns them the values 20 and 2, the solution should not change);
(2) it must be impossible for both players to simultaneously do better than the Nash solution (a condition known as Pareto optimality);
(3) the solution must be independent of irrelevant alternatives (if unattractive options are added to or dropped from the list of alternatives, the Nash solution should not change); and
(4) the solution must be symmetrical (if the players reverse their roles, the solution remains the same except that the payoffs are reversed).
Source: http://search.britannica.com/bcom/eb/article/5/0,5716,117275+6,00.html