You don’t have to be a mathematician to have a feel for numbers. โ John Forbes Nash, Jr.
Every game is a pursuit of optimal strategy. โ John von Neumann
Know yourself, know your enemy, a hundred battles you need not fight. โ Sun Tzu
Prof. Maurรญcio Veloso Brant Pinheiro
(Dep. de Fรญsica/UFMG)
Summary: Game Theory is an essential discipline for understanding strategies and decisions in competitive and cooperative situations. It transcends the universe of games, applying to various fields such as economics, political science, biology, business, artificial intelligence, psychology, and ethics. Game Theory stands out as a powerful analytical tool, providing deep insights into how strategic decisions shape interactions in real-world situations. Additionally, it discusses ethical implications, addressing fundamental questions about cooperation, competition, and fairness in complex decisions. The integration of Game Theory with Artificial Intelligence unlocks vast potential for developing advanced strategies and solving complex problems. Its interdisciplinary nature offers a deeper understanding of intricate strategic interactions and decision-making, thereby impacting a variety of fields from economics and political science to science and technology. Game Theory continues to play a crucial role in the analysis and understanding of human behavior, while driving significant advances in the evolution of Artificial Intelligence.
1. Introduction
This article offers an in-depth analysis of Game Theory, a multidisciplinary field of study that, although rooted in strategies associated with games of chance, has evolved significantly to find applications in a wide range of fields, including economics, political science, biology, business, artificial intelligence, psychology, and ethics. The importance of this theory lies in its exceptional ability to break down and examine strategic decisions, as well as the ramifications of these decisions in a variety of real and complex scenarios.
The purpose of this article is to provide a detailed and accurate understanding of Game Theory. We will begin with a historical analysis, examining the evolutionary trajectory of strategy and chance games. This chronological review will be followed by an investigation into the origins and progress of Game Theory, with special emphasis on the events and significant discoveries that have shaped its development over time.
Next, this article will address the fundamental principles and essential mathematical concepts of Game Theory. Key concepts will be detailed and explained, accompanied by practical examples of zero-sum and non-zero-sum games. The analysis will include the strategies used by players in different contexts, providing a clear view of the decision-making process and its consequences in a range of scenarios. This segment aims to demonstrate, in a didactic and accurate way, the application of theoretical principles in practice, elucidating how strategic choices affect outcomes in various situations.
In the following parts of the article, a reflection on the application of Game Theory in politics will be presented, followed by an in-depth discussion on its influence in the sphere of Artificial Intelligence.
In this context, we will emphasize how the theory contributes to the development of adaptive algorithms, capable of operating efficiently in dynamic and constantly changing environments. Furthermore, we will address the intrinsic ethical implications of Game Theory, exploring in a careful manner how it deals with fundamental concepts such as cooperation, competition, and fairness, especially in complex and multifaceted scenarios.
At the end of this article, it is expected that the reader will not only understand the fundamental aspects of Game Theory but also recognize its influence and applicability in various areas. The intention is to provide a comprehensive perspective that allows the reader to decipher strategic interactions and make more informed decisions in different contexts. We will proceed with the exploration of this fascinating field and its numerous applications.
2. Strategy and Chance Games

Strategy Games and Chance Games have played fundamental roles in the trajectory of humanity, going beyond mere entertainment. They are two distinct categories that represent a stark contrast between the strategic thinking present in Strategy Games and the uncertainty associated with luck, a central feature of Chance Games. Both practices have ancestral origins, dating back to ancient civilizations that sought mental challenges and fun through primitive forms of these playful activities.
As civilizations prospered and evolved, Strategy Games diversified as well, exerting influence not just in entertainment but also in shaping strategic thinking in ancient societies. This evolution culminated in the worldโs most widespread board games, Chess and Go.
Today, Online Strategic Video Games represent the pinnacle of digital entertainment evolution, redefining new generations’ interaction with technology and emerging as the primary form of leisure for children and teenagers. Driven by advances in Artificial Intelligence, these games offer high-quality graphics, engaging narratives, and extensive worlds, attracting both young people and adults to immersive experiences and complex challenges. Their popularity is evident in the growing community of players who gather online for competitions, collaborations, and international e-Sports events.
Unlike Strategy Games, in Chance Games, the dynamics are determined by chance, with players relying on luck to achieve success. Currently, Chance Games enjoy a global presence, found in a myriad of casinos spread across different continents. These establishments, true centers of entertainment and betting, have become emblematic destinations for those seeking fun and fortune, whether in glamorous casinos in Las Vegas, United States, or in sophisticated complexes in Macau, China, attracting eager players from all around the globe.

Among the most widespread forms of Chance Games, lotteries stand out. They represent a classic form of gambling that transcends borders, attracting participants with the promise of substantial prizes and the thrill of the unpredictable draw. The simplicity of participation and the diversity of lottery formats contribute to their enduring popularity and the formation of enthusiastic communities of players around the world.
The recent rise of online sports betting has marked a revolution in the landscape of contemporary gambling, reaching unprecedented popularity. Specialized digital platforms offer the opportunity to bet on an impressive variety of sports events, from soccer matches to horse races, providing enthusiasts with the thrill of actively participating in sports outcomes while testing their luck.

When analyzing the impacts of these games on culture and human interactions, we notice that strategy games foster cognitive development, social interaction, stress relief, creative stimulation, and mathematical learning. However, these benefits are also present in chance games, which offer a unique and accessible experience to a variety of participants.
Game Theory, a discipline that investigates strategies, decisions, and interactions in competitive contexts, applied to both categories, offers a flexible analytical framework that adjusts to the specific nuances of each type of game. By examining strategic dynamics and interactions between players, this theory provides valuable insights for winning strategies in strategy games and strategies for mitigating losses in chance games.
3. The History of Game Theory
Next, before presenting a more detailed view of Game Theory, we will briefly explore some significant milestones that contributed to the development of this field. By understanding the historical evolution of Game Theory, we can better contextualize the concepts and principles that form the basis of this interdisciplinary discipline.
3.1. Pascal, Fermat, and the Probabilities in Gambling Games
Although Game Theory, as we know it today, is a product of the 20th century, its origins date back to the 17th century, thanks to the French mathematicians Blaise Pascal and Pierre de Fermat.
In 1654, Blaise Pascal and Pierre de Fermat, two renowned mathematicians, began a correspondence (translations of the letters are available in the archives of the University of York) that would become a milestone in the development of mathematics and game theory. They dedicated themselves to studying questions of probability, a crucial element for game theory.
The focus of their study was the “problem of points,” proposed by the gambler Chevalier de Mรฉrรฉ. This problem involved a gambling game for two players with equal chances of winning each round. If the game were interrupted before one of the players reached the pre-agreed number of wins to claim the prize, how should that prize be fairly divided?

Blaise Pascal (1623-1662) was a French mathematician, physicist, inventor, and philosopher whose legacy significantly influenced various areas of knowledge. Born in Clermont-Ferrand, Pascal showed remarkable talent from a young age, developing his skills in mathematics and science. His most significant contribution to mathematics came in the form of his correspondence with Pierre de Fermat, where together they established the foundations of probability theory. This groundbreaking work, published posthumously under the title “Traitรฉ du Triangle Arithmรฉtique,” provided a solid basis for the analysis of gambling, statistical predictions, and decision-making under uncertainty. In addition to his contributions to probability, Pascal also invented the mechanical calculating machine, known as the “Pascaline,” one of the first mechanical calculators in history. His foray into physics resulted in Pascal’s Law, which describes the principle of pressure transmission in fluids, and his investigations into the vacuum contributed to the further development of the kinetic theory of gases. As a philosopher, Pascal is remembered for his writings, especially the “Pensรฉes,” in which he explored existential questions and the relationship between faith and reason. The life and work of Blaise Pascal reflect a brilliant and multifaceted mind that left an indelible mark on the intellectual and scientific landscape of the 17th century.
The solutions proposed by Pascal and Fermat for the problem of points were fundamental in establishing the principles of modern probability. They suggested that the fair division of the prize should be based on the concept of expected value, which is the sum of the probabilities of each possible outcome weighted by their respective gains. In other words, the division of the prize should reflect each player’s chances of winning the game at the moment of interruption. This approach was revolutionary as it introduced the idea of mathematically calculating probabilities, considering all possible future outcomes of the game, not just past results. This concept of expected value has become a cornerstone not only in probability theory but also in many other areas, including economics, finance, and decision-making under uncertainty.

Pierre de Fermat (1601-1665), a French lawyer and mathematician, is revered for his notable contributions to number theory and analytical geometry. Originating from the town of Beaumont-de-Lomagne, Fermat began his professional journey in the legal field, but his true fascination lay in mathematics. He was immortalized by the enigma of Fermat’s Last Theorem, a conjecture that challenged the mathematical community for centuries and was only definitively resolved long after his death, in 1995, thanks to the work of mathematician Andrew Wiles (Jean Luc Piccard unsuccessfully attempted it in the 24th century). Beyond this notable issue, Fermat left his mark on probability theory. In collaboration with Blaise Pascal, he played a crucial role in developing the foundations of this theory, exploring concepts associated with games of chance in their extensive correspondence. His innovative approach laid the groundwork for applying mathematical methods in the analysis of games of chance, a contribution that continues to resonate in contemporary statistical sciences and game theory. The life and legacy of Pierre de Fermat are true testaments to the lasting impact his analytical mind had not only in mathematics but also in interdisciplinary fields, marking him as a unique figure in the history of scientific thought.
This work not only solved a practical problem in games of chance, but also became a significant milestone in the development of Game Theory. Moreover, it established important foundations for the mathematical analysis of conflict situations and decision-making under uncertainty, especially in contexts where participants have antagonistic interests. Thus, the correspondence between Pascal and Fermat represented a significant advancement in the application of mathematics in strategies and probability.
3.2. Utility, Carl Menger, and the Marginal Utility Theory
Utility, a crucial concept developed by philosophers like Jeremy Bentham (1748 – 1832) and John Stuart Mill (1806 – 1873), plays a fundamental role in both Economics and Game Theory. This central idea focuses on the notion that people’s decisions are shaped by the utility they perceive or the satisfaction they expect to gain from different options. Simply put, when someone makes a choice, they are, consciously or unconsciously, evaluating which option will bring them more satisfaction or benefit. For instance, when choosing between two products, an individual tends to opt for the one they believe will provide greater happiness or utility. This concept is particularly relevant in situations of uncertainty, such as in gambling, where choices are often based not just on objective calculations, but also on subjective expectations and emotions.
The purchase of a lottery ticket is a perfect example to illustrate the complex interplay of rational and emotional factors in human decisions. Rationally speaking, the odds of winning the lottery are incredibly low, which, if considered in isolation, might discourage the purchase. However, the decision to buy a lottery ticket transcends this purely rational logic. It encompasses the pleasure and excitement of the game, the expectation of winning, and the dreams related to the use of the prize. These emotional and subjective elements increase the perceived utility of buying a lottery ticket. People, in general, seek to maximize their total utility, weighing both rational and emotional factors. Thus, despite the low objective probability of victory, the emotional and subjective utility of participating can be high enough to justify the ticket purchase. Therefore, the concept of Utility offers us a broader view, demonstrating that human decisions are not just products of objective calculations, but are also strongly influenced by a variety of rational and emotional factors.
In the 19th century, Austrian mathematician Carl Menger (1840-1921) introduced the Marginal Utility Theory, a fundamental pillar for understanding economic behavior. According to Menger, Marginal Utility, a central concept in economics, refers to the additional satisfaction gained from consuming an additional unit of a good or service. A common example is the experience of eating pizza: the first slice usually brings great pleasure, but satisfaction tends to decrease with subsequent slices. This pattern of decreasing marginal utility also applies in contexts like gambling, exemplified by the purchase of lottery tickets. Initially, buying the first ticket generates high marginal utility, driven by novelty and excitement. However, the utility of additional tickets usually decreases as the novelty fades and the reality of the low chances of winning becomes more apparent. Thus, the Marginal Utility Theory explains why people might be drawn to buy one ticket, but hesitate to buy many, and why the motivation to continue playing can diminish over time.
These concepts reflect the complexity of human decisions, where emotional and rational factors interact in decision-making in situations of risk and uncertainty.

Marginal Utility refers to the additional satisfaction a person gets from consuming an extra unit of a good or service. For example, when eating pizza, the first slice may provide great satisfaction, but the second may be less rewarding, and the third even less so. The marginal utility of the third slice of pizza is lower than that of the second, following a decreasing trend as consumption increases.
The Marginal Utility Theory can be used to explain a variety of economic phenomena, including:
- The Law of Demand: the law of demand states that, ceteris paribus (“all other things being equal”), the demand for a good or service decreases as its price increases. This happens because the marginal utility of an additional unit of a good or service decreases as the price increases.
- Consumer Choice: consumer choice is the process by which consumers decide what goods and services to buy. The Marginal Utility Theory can be used to explain how consumers make their choices.
- The Law of Supply and Demand is a balance that determines the price of a product. With supply representing the available quantity and demand indicating the desire to buy, the Marginal Utility Theory explains how people decide how much they are willing to pay. As supply increases, marginal utility decreases, leading to a market equilibrium point, where buyers and sellers agree on the price. The Marginal Utility Theory helps to understand how individual choices impact this dynamics between supply and demand.
3.3. Morgenstern and von Neumann: The Birth of Modern Game Theory
In 1944, the book โThe Theory of Games and Economic Behavior,โ written by Hungarian mathematician John von Neumann and American economist Oskar Morgenstern, marked the beginning of modern Game Theory. This seminal work introduced fundamental concepts of game theory, such as the Value of a game and the Minimax Theorem, which are strategies for minimizing the maximum loss or maximizing the minimum gain in a game.
The Payoff of a Game refers to the outcome that each player can expect to receive if all players choose their best strategies. It pertains to the expected outcome or average gain that a player can achieve by following a specific strategy in a game.
The Minimax Theorem, often associated with zero-sum games where one player’s gain is directly proportional to the other’s loss, has a broader range of applications. Fundamentally, the theorem reflects the strategy of minimizing the potential maximum loss, considering the most effective play of the opponent. This principle is widely employed in both decision algorithms and game theory to determine the most advantageous move, under the premise that the adversary is also playing optimally. Its utility extends to games involving multiple players, demonstrating that minimax is a valuable tool in a variety of contexts to help players reduce their maximum losses and plan against the best strategies of their opponents.
Furthermore, von Neumann and Morgenstern anticipated the concept of Nash Equilibrium, a state in which no player can improve their situation by unilaterally changing their strategy.

Zero-sum games represent situations where one player’s gain is exactly balanced by the other’s loss, resulting in a total sum of rewards equal to zero. In other words, what one player gains, the other inevitably loses, and vice versa. In the event of a tie, both players receive no reward. Examples of zero-sum games include Odd or Even, Tic-tac-toe, and Rock-Paper-Scissors. The strategies adopted by players in zero-sum games typically involve maximizing their own gain while simultaneously minimizing the opponent’s advantages. A Constant Sum Game, a first generalization of the Zero Sum Game, is trivially reducible to a Zero Sum Game.
3.4. John Nash
John Nash, born in 1928 in Bluefield, West Virginia, was a world-renowned mathematician. His undeniable talent led him to the Massachusetts Institute of Technology (MIT), where he received his education. In 1948, Nash joined Princeton University, one of the most prestigious institutions in the world. There, he was a doctoral student and, later, a professor and senior researcher.

John Forbes Nash Jr.: his remarkable work in Game Theory earned him the Nobel Prize in Economics in 1994. Despite personal challenges caused by schizophrenia, his enduring contributions in the fields of mathematics and economics stand out as one of the brightest minds of his generation. Immortalized in the book and movie “A Beautiful Mind,” Nash died in a car accident in 2015, but his legacy as a pioneering mathematician and economist lives on.
During his time at Princeton University, John Nash made a notable contribution to Game Theory by presenting his doctoral thesis titled “Non-cooperative Games” in 1950. The following year, he published a corresponding paper in the prestigious Annals of Mathematics journal. This seminal work revealed innovations by introducing the revolutionary concept of non-cooperative Nash Equilibrium.

Nash Equilibrium: It is a stable state in which no player can improve their position by unilaterally changing their strategy, as long as the other players maintain their strategies.
Let’s consider that two players choose strategies, a set of tatical moves and contra-moves, denoted by P = {p1, …, pn} and Q = {q1, …, qm}. In this context, the pair (Q, P) forms a Nash Equilibrium, this means that neither of the players can improve their outcome by changing their strategy while the opponent keeps their choice constant. In practical terms, if the player with strategy P cannot achieve a more favorable outcome by changing their strategy, given that the player with strategy Q remains with their original choice, and vice versa, then a state of equilibrium is reached. In this state, known as Nash Equilibrium, any unilateral change in strategy does not provide an advantage to any of the players.
This equilibrium, applied to games where players do not cooperate with each other, represents a stable state in which each participant adopts the optimal strategy, taking into account the strategies of the other players. Nash’s contribution in this context not only solidified his position as a prominent figure in Game Theory but also left a lasting legacy that continues to influence various disciplines, from economics to political science.
A classic example of how Nash equilibrium applies is the Prisoner’s Dilemma, as we will see in detail later. In this scenario, two prisoners are interrogated separately and have the option to confess or remain silent. Each prisoner’s decision to confess or not influences the penalties of both. The non-cooperative Nash Equilibrium occurs when both confess. In this state, each prisoner seeks the best strategy, given the choice of the other, creating a mutual incentive for confession.

Non-Zero-Sum (and non-constant) Games represent an essential category in Game Theory, distinguished from zero-sum games by the possibility for participants to achieve outcomes in which there is not an exact compensation between gains and losses. In other words, in this context, players have the opportunity to achieve mutual gains by strategically collaborating to obtain beneficial results for both parties. The Prisoner’s Dilemma is a clear, albeit atypical, example of a non-zero-sum problem.
Nash’s work was fundamental for the advancement of Game Theory. He highlighted the utility of game theory in analyzing conflict situations where cooperation among participants is limited. The non-cooperative Nash Equilibrium is a powerful concept with applications in various areas, such as economics, politics, psychology, and law. It provides valuable insights in business competitions, diplomatic negotiations, war strategies, and consumer behavior. Nash’s life and work continue to inspire mathematicians and scientists around the world. His lasting impact on game theory and other areas of mathematics is a testament to his genius and dedication to the pursuit of knowledge.
4. Game Theory in a Nutshell
Game Theory, at its core, explores scenarios in which agents make strategic decisions, considering the consequences resulting from their interactions. Through the use of mathematical tools, this theory models and analyzes dynamics, revealing patterns and optimal strategies. Below, we will concisely address the fundamental concepts of Game Theory and how it operates, using simple examples.
4.1. The Payoff Matrix: Game of Even or Odd
In Game Theory, the payoff matrix is the central concept that quantifies the consequences of strategic choices in competitive interactions between two players. Each element of the matrix reflects a quantified gain assigned to player A (Alice) when she chooses a particular strategy, while player B (Bob) chooses another specific strategy, and vice versa.

The game of Even or Odd is a simple form of competition, where one player emerges victorious while the other faces defeat (the sum of the gains of the first player is equivalent to the negative gains, or losses, of the second). In each round of Even or Odd, Alice has the option to choose between two specific moves: showing a number from 0 to 10 that is either even or odd. Similarly, Bob makes his choice between these two possibilities. After these decisions, the numbers chosen by Alice and Bob are revealed, and the sum of these numbers determines whether the result is even or odd, thus defining the winner. The victory goes to the one who, even before the play, made the correct choice about whether the total would be an even or odd number.
Consider the Even-Odd Game, a notable and simple example of a two-player zero-sum game. The outcomes of the confrontations between Bob and Alice can be more clearly understood through the following table, where each entry represents a pair of payoff values corresponding to Alice’s victory and Bob’s defeat (+1, -1), and vice versa (-1, +1). These values depend on the strategic choices of each player in the round.

Considering that each entry in the table represents a pair of values, it can be subdivided into two Payoff Matrices. In the first matrix, we will have Alice’s (A) gains/losses, and in the second, those of Bob (B). Each element of the matrix represents the gain/loss of Alice (or Bob) for specific plays by both (strategies that index the rows and columns). Thus, these matrices are:

As it is a Zero-Sum Game (note how the element-by-element sums of the two matrices above cancel each other out), when Alice wins (+1, -), Bob loses (-, -1), and vice versa, which makes the elements of the matrix equal in absolute value but of opposite signs. There is also no possibility of ties, meaning there are no elements in the matrices where the gain is zero.
The mathematical representation of the potential outcomes of all the players’ strategies, confronted one by one and expressed in the payoff matrices, is fundamental for analyzing, in a broader context, the dynamics of strategic choices over several plays (In this scenario, Linear Algebra stands out as the central tool in Game Theory, providing a solid basis for the analysis of these interactions). Understanding the payoffs is crucial for identifying optimal strategies encoded in strategy vectors and calculated in the expected values of the game, as we will see next.
4.2. Strategy Vectors and Expected Value: Rock-Paper-Scissors
In the language of Linear Algebra, the strategy vectors for Alice (P) and Bob (Q) are vectors whose components correspond to the probability of a specific player resorting to a specific move, based on a given outcome matrix.
Formally, the strategies of both players are encoded in these vectors, outlining the probabilities associated with each choice in the context of their own Payoff Matrix. In a more general case of a game where Alice has n choices and Bob has m, we will have:

The expected value of the game E(P,Q) is the expected payoff for Alice over many games, calculated by confronting Alice and Bob’s strategies encoded in the strategy vectors P and Q.
In a more general case of a game where Alice has n choices and Bob has m, we will have:


where:

and PT is Alice’s transposed strategy vector (column vector โ row vector), A is Alice’s payoff matrix, and Q is the vector encoding Bob’s strategy. The Expected Value of the game, therefore, represents the outcome for one of the players in the confrontation of both players’ overall strategies, expressed in the two strategy vectors. This value is obtained as the weighted average of payoffs in all possible confrontation situations. In a zero-sum game between two players, Alice’s expected value, E(P,Q), will be equal, by definition, to the opposite of Bob’s expected value, โE(Q,P).
Following the example of Even or Odd, consider another game between Alice and Bob: the Rock-Paper-Scissors game.

In the Rock-Paper-Scissors game, the two players (Alice and Bob) simultaneously choose one of three options: rock (a clenched fist), paper (an open hand), or scissors (a scissor gesture with the fingers). The basic rules determine that rock crushes scissors, scissors cut paper, and paper covers rock. The game is resolved instantly, revealing how simple choices can result in dynamic and unpredictable interactions.
The result table (for Bob) is:

This table also generates two matrices (one for Alice and another for Bob). From this point forward, we will analyze the game from Alice’s perspective, using the payoff matrix A, which is composed of the second payment values from each pair of values in the entries of the table above.

As we saw, strategy vectors are outlined by their components, which express the probabilities of a player opting for a specific move. Since these probabilities are normalized, the sum of the components is always equal to one.
For example, if the probability of Alice choosing paper is 50%, while the probabilities of choosing rock or scissors are 25% each, Alice’s strategy vector will have components of 1/4, 1/2, and 1/4, respectively. In summary, for both Alice and Bob, we have two vectors: P (Alice’s strategies) and Q (Bob’s strategies). These vectors, represented through their components (p1, p2, p3) and (q1, q2, q3), encode the probabilities associated with each of the players’ choice of moves:

Let’s consider, for example, the situation where Alice’s and Bob’s strategies consist of choosing, respectively, Rock (1,0,0) with a 100% probability, while Bob chooses Paper (0,1,0) also with a 100% probability. In this case, the expected value indicates that the victory is Bob’s with a gain of +1 (-1 for Alice):

It’s important to note that if the choices are completely random, the probabilities of each strategy are equal, and over many games, the results will converge to a tie.

Even in scenarios of randomness, convergence to a tie is not an absolute certainty, but rather a statistical tendency. The unpredictable nature of random choices can occasionally lead to fluctuations in outcomes, allowing some strategies to temporarily stand out.
4.3. Optimal Strategies, The Minimax Theorem, and The Saddle Point
Consider now two specific strategies, P* and Q*, for any sets of strategies P and Q (of Alice and Bob). These strategies are designated as optimal for the players Alice and Bob, respectively. The value of the game, represented by the expected payoff E(P*, Q*), is reached when both players employ their optimal strategies P* and Q*. Furthermore, we have:

This inequality is a consequence of the Minimax Theorem, which asserts the existence of optimal strategies P* and Q*, within a set of strategies P and Q, that maximize the gain of one player and minimize the gain of the other when combined with the adversary’s strategies. In other words, the Minimax Theorem essentially suggests that, faced with uncertainty about the opponent’s move, it is prudent to choose the strategy that minimizes the maximum potential loss E(P*, Q*).
This concept is manifested in what is called the saddle point, which, in the context of game theory, represents a stable solution with respect to the strategies of the players (it’s important to note that this differs from a stable equilibrium). In simpler terms, a saddle point denotes a set of strategies where, if both players are executing their chosen strategies, neither will have a reason to modify their approach, considering only the actions of the other. In zero-sum games, where one player’s gain is exactly equal to the other’s loss, a saddle point characterizes a set of strategies where neither player has an incentive to unilaterally change their strategy, given the response of the other player. If the payoff matrix has a saddle point, the game becomes strictly determined.
Formally, the Minimax Theorem can be presented in the following way:
Let X โ โโฟ and Y โ โแต be sets that are both convex and compact. Consider the function f: X ร Y โ โ, which is continuous and has concave-convex properties. This means that:
- For a fixed y, the function f(ยท, y): X โ โ is concave.
- For a fixed x, the function f(x, ยท): Y โ โ is convex.
Accordingly, it is established that:

This result implies the existence of a saddle point for the function f in the Cartesian product of X and Y.
In the special case of a Bilinear Function: The theorem is especially valid when f(x, y) is a function linear in both of its arguments, making it bilinear, since a linear function is both concave and convex. Therefore, if we have f(x, y) = xแตAy, where A is a finite matrix in โโฟหฃแต, the equality is presented as follows:


The bilinear function situation is especially important in the context of zero-sum games. In these games, the players’ strategy sets consist of lotteries over their actions (mixed strategies), and the returns are calculated from the expected value. In the figure above, the z-axis is given by the values of A, Alice’s payoff matrix. In zero-sum games, the saddle point of the Minimax Theorem is also a Nash Equilibrium. This is because the strategies that minimize the maximum loss in a zero-sum game are also the best responses to the strategies of the other players, thus satisfying the definition of a Nash Equilibrium.
In games that are not zero-sum, all saddle points are Nash Equilibria, but not all Nash Equilibria are saddle points. Therefore, while the Minimax Theorem specifically deals with optimal strategies in zero-sum games, the Nash Equilibrium provides a broader view of strategic stability in a variety of games, including, but not limited to, zero-sum games.
4.3. the Prisoner’s Dilemma
The Prisoner’s Dilemma was formally addressed for the first time in the 1993 book titled ‘Prisoner’s Dilemma,’ written by William Poundstone. This work provides an intriguing perspective on contemporary situations, offering valuable insights through the analysis of this complex game.
In summary, the scenario involves two members of a gang who are arrested without communication between them. The police, with limited evidence, plan to sentence them to one year in prison for a minor offense.
Then a Faustian bargain arises from the police: each prisoner can testify against the other, offering a chance to be released, while the other would face a longer sentence. If both testify, they both receive an intermediate sentence of two years. This situation illustrates the conflict between self-interest and mutual benefit, highlighting how cooperation would be more advantageous, although self-defense often prevails.

The Prisoner’s Dilemma presents four possible outcomes for prisoners A and B. If both choose to remain silent, they will each serve one year in prison. If A decides to testify against B while B remains silent, A will be released, while B will face a longer sentence of three years. If A chooses to remain silent but B decides to testify against A, A will serve three years, and B will be released. Finally, if both choose to testify against each other, they will both receive a two-year sentence.
Let’s call A as Alice and B as Bob, the two prisoners. The payoff matrix for Alice, with outcomes quantified in years of prison, is:

Since Alice’s gains are measured in years in prison, the best outcome for her is the one with the lowest gain, which is 0. With this in mind, we can construct the payoff matrices for both prisoners:

Note that the payoff matrices are not symmetrical, and besides that, this is not a zero-sum game since:

The strategies of Alice (P) and Bob (Q):

where the asterisk indicates the case in which the prisoners remain silent. Thus, we can calculate the expected values for all possible situations in the Prisoner’s Dilemma:
1) Alice remains silent and Bob testifies, resulting in a 3-year sentence for Alice:

2) Alice testifies and Bob remains silent, Alice is acquitted:

3) Alice and Bob both remain silent, both receive a one-year sentence.

4) Alice and Bob both testify, both receive a two-year sentence.

So we can order the expected values and highlight Alice’s best strategy, which in this case is defined by the least gain in prison years (0):

This inequality, in fact, is a consequence of the Minimax Theorem, which tells us that there are optimal strategies P* and Q* that maximize the gain of one player and minimize the gain of the other when combined with any other strategies. In other words, this theorem essentially tells us that when faced with uncertainty about your opponent’s move, you should choose the strategy that minimizes your maximum potential loss. Neither of them has reasons to change their strategy considering only what the other is doing.
From Alice’s perspective, if she trusts Bob to cooperate (remain silent), her best outcome is 1 year. But what if Bob betrays her? Then, confessing gives her 3 years. Applying the Minimax Theorem, Alice should confess, regardless of Bob’s assumed action. The same logic applies to Bob. He should also confess, minimizing his potential loss to 2 years (better than the 3 years for remaining silent if Alice betrays him). This results in the Nash Equilibrium: the outcome where both players choose the strategy that minimizes their worst scenarios, even if it leads to a suboptimal result for both (2 years each if they cooperated).
In Alice’s result matrix, the saddle point corresponds, therefore, to the element a22 = -2, which is the smallest element in its row and the largest in its column. Once the saddle point is known, if both players are employing their optimal strategies, neither has reasons to change them considering only what the other is doing, as they represent the best choice for each player, regardless of the choices made by the other player. In a zero-sum game (where one player’s gain is equal to the other’s loss), the existence of a saddle point means that no player has the incentive to unilaterally change their strategy, given what the other player is doing. In this case, the game becomes strictly determined.
On the other hand, the Minimax Theorem, in the context of the Prisoner’s Dilemma, highlights the inherent difficulty of achieving cooperation in situations where individual incentives favor betrayal. It shows the delicate balance between trust and self-preservation in strategic interactions, leaving us to ponder, for example, whether cooperation can arise in a world governed by self-interest?
Although, in the previous situations, these probabilities have been treated as exclusively zero or one, it is crucial to note that they are not necessarily restricted to these values. Both Alice and Bob can, by taking into account each other’s actions, develop customized strategy vectors that incorporate the probabilities of avoiding capture or receiving the maximum penalty. Any outcome where both players are playing a dominant strategy is automatically a Nash Equilibrium.
It is important to note that not all games have dominant strategies, and the presence of dominant strategies depends on the specific rules and interactions between players in a given context. However, when they exist, they play a crucial role in predicting outcomes and understanding strategic dynamics in game situations.
5. Reflections on Game Theory in Politics
Game Theory, originally developed to analyze competitive and cooperative situations in games, has transcended its origins and found crucial applications in a variety of fields. These fields, where decision-making is essential to understand and model strategic interactions among different agents, include economics, political science, biology, business, artificial intelligence, psychology, and ethics.
Game Theory’s ability to represent complex interactions among independent and rational decision-makers makes it a robust tool for exploring dynamic scenarios. In these scenarios, the choices of one agent directly impact the options and outcomes of others. In economics, for example, it is frequently used to analyze market strategies, competition, and price formation. In political science, it helps in understanding the behavior of countries in international relations, diplomatic negotiations, and coalition formations. In biology, Game Theory is applied to model evolutionary strategies and competition among species. In business, it offers insights into negotiation strategies, collaboration, and competition in the business environment.
In particular, Game Theory also has significant ethical implications, providing a conceptual basis for examining moral dilemmas, ethical cooperation, and equity strategies in complex decisions involving multiple agents. The Prisoner’s Dilemma, a famous problem in Game Theory, encapsulates the tension between individual and collective interests. It highlights how collective altruism can result in a less favorable outcome for both. Notably, loyalty to the partner appears irrational in this context. The Prisoner’s Dilemma has been used to model a wide range of situations, including conflicts between nations, competition among companies, and even the spread of diseases.
The ancient Greeks encapsulated this idea of equilibrium with the principle of ‘Nothing in excess!’, highlighting the importance of moderation in all things. Aristotle, one of the forerunners of Western thought, placed enormous value on balance, both individually and collectively. He argued that moral virtue arose from finding the midpoint between two opposite extremes, a central concept in his ethics of virtue. Moreover, Aristotle applied the concept of balance in his political and social analyses, promoting a mixed constitution in which different forms of government complemented each other to ensure stability and justice. For Aristotle, balance was more than a mere virtue; it was an essential pillar for a virtuous life and a just and stable society.
Let’s imagine a scenario with two political extremes: on one side, a totally libertarian, anarcho-capitalist regime, where individual freedom is absolute; and on the other, a totalitarian socialist regime, where there is no individual freedom, and the state controls all aspects of the individual in society. Each regime has its own ideals and values.
What would then be the suboptimal result, or the Nash equilibrium (static), for a game between two actors following these ideologies? Theoretically, it would be a state where there is still freedom, but citizens must give up some of that freedom for the collective, following basic rules so as not to harm each other. This equilibrium reflects the search for a synthesis between individualism and collectivism, recognizing that both individual freedom and collective responsibility are essential for overall well-being.

Political Balance
To better understand this phenomenon in the context of Game Theory, we can use the analogy of an RLC circuit in politics. Imagine a socialist revolution leading to a totalitarian regime as an inductive element, initiating the process with a strong tendency in one direction (e.g., left: negative current, discharge, on our ammeter).
If we imagine an ammeter with zero in the center, the needle’s oscillations to the sides would represent the shifts in power and political trends over time. When the needle moves to one side, it indicates an inclination towards a type of governance or ideology. When it moves to the other, it reflects the rise of an opposing force. Ideally, a healthy democratic system would cause the needle to oscillate around the center, with decreasing amplitude, indicating a dynamic balance between different forces and ideas. However, exaggerated polarization can cause these oscillations to become more extreme, making it difficult to return to the central balance point, and in an extreme case, depending on the external force, leading to rupture.

Then, a conservative uprising leads to democratization that acts as a capacitive element, introducing an opposing force that seeks to balance and moderate this initial tendency, leading the current in the completely opposite direction (right).
As politics evolve, democratic oscillations occur, similar to the current oscillations in a damped RLC circuit. These oscillations represent the alternation of power and the various political forces in action in an infinite Game of interests (Machiavellianly detached from morality). If the political scenario were only guided by pre-established interests, the dynamics would be simple and predictable, leading to a static Nash equilibrium state. In this context, a natural balancing between the two dominant ideologies would be expected.
However, the political dynamic is constantly changing, especially with the arrival of new actors who shift the previous balance, something comparable to an external force disturbing a system in equilibrium.
The survival of an ideal state is similar to an evolving ecosystem, where different levels of natural selection act (Multilevel Selection Theory). In this scenario, just as animals need to balance their individual interests with those of the group to survive, citizens must find a middle ground between their personal freedom and the needs of the community. Therefore, both individual freedom and collective responsibility are fundamental for the well-being of society, just as the survival of the individual and cooperation within a group are essential for the evolution of species. This is the eternal dilemma between individualism and altruism.
In an evolutionary system, however, the saddle point is, of course, a dynamic fact. This means that the values in the payoff matrix, which determine the rewards or losses for the strategies chosen by the players in a game, can change over time. These changes can be the result of adaptations, mutations, or environmental alterations, reflecting the dynamic and adaptive nature of evolutionary systems both at an individual and a collective level. Therefore, the analysis and prediction of such systems require an understanding of the dynamics of the saddle point and the conditions that influence changes in the payoff matrix.
In the current political sphere, the rising polarization is intensified by the exponential development of Artificial Intelligence technologies, especially evident in the impact of social networks. The influence of social networks on political polarization makes dialogue and consensus even more difficult. People tend to group into single-thought communities, known as social bubbles or echo chambers. Within these spaces, they are often exposed only to ideas that reinforce their already established views, creating a continuous cycle of reaffirmation that challenges openness to alternative perspectives. This phenomenon significantly amplifies the challenge of finding common ground between divergent ideologies.
In this scenario, the dynamics of political equilibrium resemble a complex game in game theory, reminiscent of the Nash equilibrium concept. Here, stability is continually challenged and subject to rapid changes, especially in extreme situations (e.g., exponential technological advancement). These conditions can lead to significant disruptions and chaos, analogous to a forced oscillator reaching its resonance frequency with minimal resistance.
This phenomenon highlights the way in which the constant interaction between conflicting strategies, in the face of new developments, a key concept in game theory, can exacerbate political instability. In this context, political equilibrium is less a static state and more a dynamic process, where adaptation and response to the ever-evolving strategies of political actors are crucial. This perspective, which resonates strongly with the Zeitgeist and with the ideas of Hegel, emphasizes that politics is a continuous game of action and reaction, shaped by the constant interaction and strategic adjustment among participants.
6. Game Theory and Artificial Intelligence
Game Theory, when applied to Artificial Intelligence (AI), unlocks vast potential for the development of advanced strategies, adaptive learning, and solving complex problems.
A vivid example of this integration is evident in the prisoner’s dilemma, a common situation in AI. In this scenario, the dilemma arises when multiple agents are learning to interact in an environment that can be both competitive and cooperative. In multiplayer game scenarios, for instance, AI agents are faced with the dilemma of cooperating to achieve a common goal or competing against each other to maximize their own individual rewards.
While it might seem beneficial for the agents to adopt an immediate competitive strategy, this approach can lead to a suboptimal outcome for the system as a whole if all agents follow it. This highlights the importance of cooperation and the balance between competition and collaboration in AI.
Furthermore, in the context of cooperative multi-agent reinforcement learning, AI agents face the challenge of deciding between sharing information for collective benefit or retaining data to maximize their own individual gains. Sharing information can lead to improved group performance, but it might also expose individual strategies and vulnerabilities.
The incorporation of game theory principles into machine learning algorithms allows for the adaptation and enhancement of strategies based on interactions. For instance, a machine learning algorithm utilizing game theory can learn to play a board game, like chess, by observing and analyzing the strategies of other players. Based on this acquired knowledge, the algorithm can develop its own game tactics, highlighting the power of AI in learning and strategically evolving.

A concrete example of the application of Artificial Intelligence (AI) incorporating principles of game theory is trading algorithms, used to optimize negotiation processes. In the realm of e-commerce, these algorithms are employed to negotiate prices or delivery conditions in an automated way. For instance, when a customer wants to buy a product, AI can evaluate different strategies and counteroffers to establish a price that is satisfactory for both the seller and the buyer. This is done through analyzing various factors, such as the current market price of the product, the buyer’s willingness to pay a certain amount, and the seller’s desired profit margin. Based on this information, AI can suggest a price that optimizes benefits for both parties. Additionally, AI can be used in negotiating delivery terms. For example, it can offer a faster delivery time in exchange for a higher price, or a longer delivery time if the buyer prefers to save on shipping costs. In summary, AI-based trading algorithms aim to make the negotiation process more efficient and advantageous for all involved, representing a powerful tool that is revolutionizing online business practices.
Game Theory in Artificial Intelligence is vital for strategic decision-making and predictive analysis. It is used in various fields, from finance to cybersecurity. Game Theory driven by Artificial Intelligence enhances resource allocation and the development of competitive strategies. However, the approach faces limitations such as computational demands and unpredictability in human behavior. Understanding these principles is essential for advancing in the field of AI.
7. Conclusions
In summary, Game Theory continues to play a fundamental role in the analysis and understanding of human behavior, while driving significant advances in the evolution of Artificial Intelligence. Its interdisciplinary nature provides valuable insights that transcend the boundaries of individual disciplines, offering a deeper understanding of intricate strategic interactions and decision-making. By recognizing the ongoing relevance of this theory, we can leverage its explanatory power to tackle complex challenges across a variety of fields, from economics and politics to science and technology.
8. Acknowledgment
I express my deep gratitude to the dedicated students of the Mathematical Methods in Physics course – Linear Algebra, Guilherme Machado Egreja and Marlon Henrique Liberato, for their remarkable semester essays on Game Theory, which considerably enriched our academic understanding. Given the technical complexity of the original works, I plan to collaborate with them on a future publication, seeking a more accessible approach. In this upcoming work, we intend to perform a detailed analysis, applying Game Theory to the famous online card game Hearthstone: Heroes of Warcraft, by Blizzard, and to the battle strategies of the well-known Pokรฉmon franchise, created by Satoshi Tajiri. This project will aim to illustrate the creative and relevant use of mathematical concepts in the real context of popular games. I renew my gratitude to all students, current and past, as it is through their unique perspectives and innovations that I continue my journey of constant learning and improvement in the universe of knowledge.
9. Rereferences
- von Neumann, J. e Morgenstern, O., 1944. The Theory of Games and Economic Behavior. Princeton University Press.
- Axelrod, R., 1984. The Evolution of Cooperation. Basic Books.
- Poundstone, W., 1993. Prisonerโs Dilemma. Anchor Books.
- Osborne, M.J. e Rubinstein, A., 2004. An Introduction to Game Theory. Oxford University Press.
- Rossiter, L.H., 2006.ย The liberal mind: The psychological causes of political madness. Free World Books llc.
- Shoham, Y., Leyton-Brown, K. e Kraus, S., 2009. Multiagent Systems: Algorithmic, Game-Theoretic, and Logical Foundations. Cambridge University Press.
- Tadelis, S., 2013.ย Game Theory: An Introduction.ย Princeton University Press.
- “Altruรญsmo Recรญproco – Sua origem Biolรณgica”, Alaor Chaves 2016
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