Showing posts with label game theory. Show all posts
Showing posts with label game theory. Show all posts

Saturday, November 8, 2025

Game theory in Brazil, July 26-Aug2: Call for papers

 Marilda Sotomayor forwards the following call for papers:

Game Theory scholar. 
It is a great pleasure to invite you to participate in the 4TH INTERNATIONAL WORKSHOP ON GAME THEORY AND ECONOMIC APPLICATIONS, to be held at the University of São Paulo, from July 26 to August 2, 2026.
The workshop will offer the participants the opportunity to interact with some of the most prominent researchers in Game Theory. We expect to have over 340 participants, with a majority of young scholars and including 5 Nobel Laureates: Robert Aumann, Roger Myerson, Alvin Roth, Robert Wilson and Paul Milgrom. 
The week-long event will consist of minicourses, conferences and contributed papers sessions. The courses will start at an introductory level and will reach the frontiers of current research. Please direct questions to iwgtea2026@usp.br. 
To participate in the workshop, it is necessary to register on our website: https://www.iwgtea.fea.usp.br/, where you can also find more information on the conference. 
Limited financial aid for travel and accommodation expenses of up to 100 students or young researchers (who got his/her PhD in the last three years) will be provided. The candidate should refer to the information provided on our website. 
If you are interested in submitting a paper for presentation you should register on our website and submit it through the appropriate link. An extended abstract (up to 3 pages), or, if possible, a full paper, written in English, as well a short abstract (up to 200 words), are required. This paper will be made available for download on our website if your submission is accepted. Presentations should be made in English, the official language of the workshop. Acceptable formats for the files are PDF, PS and Word. Articles in all areas of Game Theory and its applications are welcome. 
 Please note that the deadline for paper submissions and remittance of the documents required to the young scholars is March 15, 2026. The selected candidates and articles will be announced by April 15, 2026. 
Early registration fee payment should be received by April 30, 2026. A late charge of 40% will be added after this date. Only those who have paid the registration fee by May 15, 2026, will be included in the program. The schedule of talks will be announced by the end of May.
We look forward to seeing you in São Paulo!
The Organizers
M. Sotomayor (USP), M. Bugarin (UNB), W. Maldonado (USP), R. Corbi (USP)

 

Friday, August 15, 2025

Special issue of Economic Theory in Honor of David K. Levine

 David K. Levine is celebrated:

Introduction to the Special Issue in Honor of David K. Levine  by César Martinelli , Economic Theory.  09 August 2025

"Among contemporary economic theorists, few have made substantial contributions across as many diverse research areas as David K. Levine. His publications hold significant influence among game theorists, general-equilibrium theorists, macroeconomists, political economists, experimental economists, and law-and-economics scholars.

...

"At UCLA, WUSL, EUI, and currently RHUL, he has directed sixty PhD dissertations, and counting. "

Friday, August 8, 2025

John Harsanyi: the story behind the Hungarian memorial coin (by Miklos Pinter)

 Rosemarie Nagel and Miklos Pinter have sent me the following story about how Miklos helped design the game-theoretic image on the Hungarian coin issued in memory of John Harsanyi's 100th birthday.

"The Harsanyi coin told by Miklos Pinter
The MNB (National Bank of Hungary) has a series of coins dedicated to famous Hungarians (see: MNB Collector Coins), including von Neumann, George Oláh, Imre Kertész, György Cziffra, among others.
In the summer of 2019, I was invited by the MNB to join a board responsible for planning a collector coin honoring János Harsányi on the centenary of his birth (1920). The MNB found me through one of my (former) colleagues, recognizing me as an expert on Harsányi’s contributions that led to his Nobel Prize.
I served as the scientific expert on the board. The other members included artists, coin production experts, and MNB officials. My role was to ensure the scientific "message" of the coin was accurate and meaningful. The coin designs follow a structure: one side features a portrait of the person (which was not my area), while the other side presents a motif, symbol, or image representing their scientific contribution—that side was my responsibility.
To start, I gave a talk to the participating artists (sculptors) who were preparing to submit designs. My presentation covered essential background on Harsányi and, more importantly, the main contribution that earned him the Nobel Prize: the concept of type space. With one exception, all invited artists attended. The atmosphere was pleasant; we had good discussions during and after the talk. It was informal, and I felt satisfied with how it went—it seemed the artists appreciated it too.
A few months later, the artists submitted their sketches—four or five proposals, each with a portrait on one side and a motif on the other.
Here came the surprise: the artists had clearly ignored my talk. Instead, they googled “game theory,” found images online, and based their designs on those. The proposed motifs included things like matrix games and extensive form games, which are only loosely related to Harsányi’s work. Crucially, none of the proposals reflected his key contribution involving type spaces. In hindsight, I realized this was partly my fault. In my talk, I used no visual tools—no images or illustrations—which was a mistake. Artists think visually, and my purely verbal presentation, though scientifically accurate, was practically useless for their purposes.
The board evaluated the proposals. The portraits were excellent, and the artists on the board selected the best one—it was truly beautiful, and I fully agreed, even though it wasn't my area of expertise.
The motif side, however, was a different story. I judged all the proposed designs as inadequate. They were either unrelated to Harsányi or depicted concepts associated with other scientists. I therefore recommended rejecting all of them.
The board accepted my recommendation but raised concerns: time was tight (this was already September 2019, and the coin had to be issued by May 2020), and it was unclear whether the artists could come up with a new, meaningful design in time.
Some board members informally emailed me, asking what could be done. I replied that the proposed motifs weren’t acceptable, but I shared an idea: Imagine a staircase—either rectangular or triangular—that rises or descends infinitely. In the middle of this staircase, there is a ladder stretching directly from the starting point to infinity.
They responded immediately and liked the idea. I hadn’t drawn anything—just described it in a few sentences. Later, we had a phone call, and I explained that the staircase represents a belief hierarchy, while the ladder represents a type—two different ways to reach the same end. This, essentially, is Harsányi’s insight.
They appreciated the concept even more after that conversation. The board then narrowed the selection to two artists and asked them to create a design for the motif side based on my description.
By December 2019, I received the revised designs, particularly one that I really liked. You can see it as the final version of the coin here: 👉 Harsányi Collector Coin – MNB


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Collector coin issuance on the centenary of Nobel Memorial Prize winner János Harsányi’s birth

"The Magyar Nemzeti Bank [issued] a silver collector coin with a face value of 10,000 forints and its non-ferrous metal version of 2,000 forints, on the 100th anniversary of János Harsányi’s birth, the Nobel Memorial Prize in Economics awarded scientist, on 29 May 2020. By issuing this collector coin, the MNB wishes to pay tribute to the renowned researcher of the game theory, who was a co-recipient of the 1994 Nobel Memorial Prize in Economic Sciences along with two other scientists, John Forbes Nash and Reinhald Selten ‘For his ground-breaking work in the area of non-cooperative game theory and equilibrium analysis'. The collector coins were designed by sculptor Balázs Pelcz.

"János Harsányi, a Hungarian Nobel Memorial Prize laureate in Economic Sciences, was born in Budapest on 29 May 1920. His primary field of research was game theory, he was awarded the Nobel Memorial Prize in Economic Sciences for the results he achieved in incomplete information games in 1994 as a co-recipient with John Forbes Nash and Reinhard Selten ‘For his ground-breaking work in the area of non-cooperative game theory and equilibrium analysis'. In the field of game theory, they were the first scientists to receive the Nobel Memorial Prize in Economic Sciences.

 


 

 

Thursday, June 5, 2025

Yale celebrates Larry Samuelson

 

Economist Larry Samuelson on Pioneering Game Theory Research at Cowles.  Yale professor Larry Samuelson's research was pivotal in the evolution of game theory economics. The former Cowles Foundation Director and president of the Econometrics Society sits down with Richard Panek to explain his motivations behind the work Samuelson is best known for. 

"Larry Samuelson was born in 1953 in Rockford, Illinois, then a solidly blue-collar, middle-class, Midwest industrial town. After high school Samuelson decided to go away to college—the University of Illinois at Champaign-Urbana (today, Urbana-Champaign), a three-hour drive from Rockford—although he had "not much of an idea” about what he wanted to study. Instead, he had chosen to attend college because, on the scale of good-for-me/bad-for-me, he guessed it would be more advantageous than the alternative.

"His willingness to take the road less traveled resurfaced when the time came to choose classes. He happened upon an economics course and, without knowing why, signed up. The course proved to be revelatory. The teacher was “particularly inspiring,” Samuelson says, but it was the subject itself that riveted him.

"He already knew that he liked mathematics—its “logic,” he says, its “beauty.” But in economics he discovered “an ideal blend of precision and rigor on the one hand, and relevance on the other hand.” After graduation he stayed at the University of Illinois to pursue a masters in economics and then a doctorate. “Being an economist,” he says, explaining the reasoning behind his choice of career, “you’re doing math in the service of what looked like some really important questions.”

"In the mid-1970s game theory wasn’t part of the standard curriculum in the study of economics; it was what Samuelson calls “a specialty.” Nonetheless, Illinois did offer a course on the topic, and as a graduate student Samuelson, once again electing for an option off the beaten path, took the course—and, once again, found a fortunate combination of inspiring instructor and compelling topic. One of the teachers in that class was Alvin E. Roth, future co-recipient, with Lloyd Shapley, of the Nobel Prize in Economic Sciences partly for his work on, yes, game theory.

...

"After completing his PhD in economics at Illinois, Samuelson embarked on the life of an itinerant academic. For a year he taught at the University of Florida, Gainesville, then for three years at Syracuse University, then for the rest of the 1980s at Pennsylvania State University. In 1990 he settled down at the University of Wisconsin, Madison, and there he remained for nearly two decades, before joining the faculty at Yale in 2007. Along the way Samuelson became a leading figure in two subsets of game theory in economics.

One was evolutionary game theory.

At first, the evolution in evolutionary game theory was metaphorical. From the late 1980s through the 1990s, Samuelson studied scenarios in which players would adjust their behavior over the course of repeated plays of a single game, experimenting with various actions and gravitating toward those that had tended to bring good outcomes and away from actions that had produced disappointing results. The basic question was whether such learning would lead players in a game to a Nash equilibrium, and the basic answer, albeit with many caveats and qualifications, was yes: Stable outcomes of learning dynamics are Nash equilibria.

Then Samuelson began taking the word evolution more literally, extending his mathematical work on evolutionary game theory into biology. In collaboration with Yale evolutionary biologist and ornithologist Richard Prum, for instance, Samuelson studied cases of members of a species mimicking the members of other, typically more dominant, species. The example they used in a 2012 paper was the evolution of Downy Woodpeckers that are now nearly identical in appearance to the generally larger Hairy Woodpeckers.

...

"More recently, Samuelson has extended his literal interpretation of the word evolution. Rather than using evolution to study other species, he has begun applying it to the biology of humans.  An old joke: The reason economists don’t sell their children is that they might be worth more later. And yes, Samuelson grants, “the mechanics of evolutionary selection are fundamentally selfish. Evolution selects for traits, behaviors, and preferences that increase the reproduction prospects of the individual, or indeed more precisely the gene.”

But.

“There's nothing intrinsic to economics that requires people to be selfish,” Samuelson says. Economic theory assumes that behaviors follow preferences, but it makes no assumptions about the content, whether selfish or selfless, of those preferences. “To an economist Mother Teresa is as good a model of economic behavior as is”—a pause—“Elon Musk might come to mind. Mother Teresa was as selfless as could be, but she followed that goal consistently and coherently, and one would have no trouble fitting that into an economic model.”

And because preferences “are the point of departure for models of individual behavior,” they are also the point of departure “for all of economics.” Biological and cultural evolution helped shape our preferences just as it helped shape many of our characteristics. By identifying aspects of preferences that would have conferred an advantage on our evolutionary ancestors, Samuelson’s research has allowed economists to sharpen their assumptions about preferences and therefore the subsequent economic analyses.  

In the late 1990s Samuelson began investigating the topic that would become his second major area of research: repeated games, especially the concept of reputations. As the name suggests, repeated games involve modeling that extends beyond the decision-making apparatuses of a one-off competition.

...

"By the 2010s Samuelson had become somewhat of an elder statesmen in the field of game theory economics. In 2011 he was elected to the American Academy of Arts and Sciences. The following year he received a fellowship from the Society for the Advancement of Economic Theory. From 2014 to 2020 he served as the director of the Cowles Foundation, where he initiated a homecoming of sorts: In 1934 Alfred Cowles, champion of the use of statistics in economics, helped fund the launch of the Econometrics Society, and Samuelson, in his role at the head of the Cowles Foundation, orchestrated the transfer of the Society’s office to Yale. As of 2025 Samuelson is serving as the president of the Society.

Not surprisingly his five-decade immersion in game theory has affected his view of the world. “I think about incentives a lot,” he says. “If I had to summarize all of economics in one phrase, that phrase would be: Incentives matter. That sounds trite,” he quickly adds, “but it’s something people very easily lose sight of.”

So what, I wonder, was his incentive to sit for this interview? What went through his game theorist’s brain when the current director of the Cowles Foundation invited him to be the subject of the first of what might become a series of faculty profiles on the Cowles website? Can Samuelson describe his decision in terms of game theory?

He immediately defaults to a familiar framing.

“This could be good for the organization, and indirectly that’s good for me. Or,” he goes on, after a moment’s reflection, “at least it makes me feel good about me.”





Tuesday, October 22, 2024

Stability vs. No Justified Envy, by Romm, Roth and Shorrer

 Here's a recent paper that clarifies some of the prior literature on comparing stability in two-sided matching with a related kind of envy-freeness in allocations of goods to individuals using priorities.


Romm, Assaf, Alvin E. Roth, and Ran I. Shorrer, "Stability vs. No Justified Envy," Games and Economic Behavior, Volume 148, November 2024, Pages 357-366  https://doi.org/10.1016/j.geb.2024.10.002
 
Abstract: Stability and “no justified envy” are used almost synonymously in the matching theory literature. However, they are conceptually different and have logically separate properties. We generalize the definition of justified envy to environments with arbitrary school preferences, feasibility constraints, and contracts, and show that stable allocations may admit justified envy. When choice functions are substitutable, the outcome of the deferred acceptance algorithm is both stable and admits no justified envy.

Monday, August 5, 2024

Theory brunch at Stanford

 A Sunday brunch to welcome Fuhito Kojima back for a summer visit brought together an eclectic group of Stanford theorists, past, present, and future. (Mike Ostrovsky, Mohammad Akbarpour and Bob Wilson had already run off before things settled down for this picture  of Fuhito Kojima, Ilya Segal, Itai Ashlagi, Jason Hartline, Ravi Jagadeesan, Oguzhan Celebi, Roberto Corrao, and Frank Yang.)



Saturday, April 27, 2024

No Prices No Games! Four Economic Models by Michael Richter and Ariel Rubinstein

 Here's a new book on economic theory by Richter and Rubinstein.

No Prices No Games!  Four Economic Models  by Michael Richter and Ariel Rubinstein  

At the link you can download a pdf or read it online for free, or purchase a printed edition.

"While current economic theory focuses on prices and games, this book models economic settings where harmony is established through one of the following societal conventions:

• A power relation according to which stronger agents are able to force weaker ones to do things against their will.

• A norm that categorizes actions as permissible or forbidden.

• A status relation over alternatives which limits each agent's choices.

• Systematic biases in agents' preferences.

"These four conventions are analysed using simple and mathematically straightforward models, without any pretensions regarding direct applied usefulness. While we do not advocate for the adoption of any of these conventions specifically – we do advocate that when modelling an economic situation, alternative equilibrium notions should be considered, rather than automatically reaching for the familiar approaches of prices or games."



By email, Ariel tells me that he designed the cover.

Contents

0. Introduction

(pp. 1–12)
  • Michael Richter
  • Ariel Rubinstein
  • Michael Richter
  • Ariel Rubinstein
  • Michael Richter
  • Ariel Rubinstein
  • Michael Richter
  • Ariel Rubinstein
  • Michael Richter
  • Ariel Rubinstein
  • Michael Richter
  • Ariel Rubinstein




"In the final chapter, we compare this book's modeling approaches with each other and to those of standard Game Theory on two ``battlegrounds''.
The first is the matching economy. An even-sized population of agents must match into exclusive pairs (pairings). Each agent possesses a preference relation over potential mates.
The standard cooperative game theory solution concept for matching economies is ``pairwise stability''. Following Richter and Rubinstein (2024), we compare this concept with the jungle equilibrium, the Y-equilibrium and the status and initial status equilibrium concepts.
The second battleground is a ``political economy'' situation. A group of agents hold views on a political issue. Each agent chooses a position and has preferences only regarding the position he himself chooses (and not the choices of others). However, there is a need that a majority of agents choose the same position.
Traditionally, such a situation is modeled as a non-cooperative game and its Nash equilibria are calculated. Extending Richter and Rubinstein (2021), we compare this approach with the convex Y-equilibrium and the biased preferences equilibria.
On both battlegrounds, the new approaches lead to very different outcomes than the traditional ones."

Friday, December 8, 2023

Computers in Econ (and in market design)

 The current issue of the journal Œconomia. is devoted to The Computerization of Economics. Computers, Programming, and the Internet in the History of Economics

It includes this surprisingly grumpy-sounding take on market design, particularly on its intersection with game theory:

 Nik-Khah, Edward. "The Closed Market: Platform Design and the Computerization of Economics." Œconomia. History, Methodology, Philosophy 13-3 (2023): 877-905.

Here's a paragraph that caught my eye:

"In his book Who Gets What—And Why, the market designer Alvin Roth pronounced firms such as Google, Amazon, and Uber to be “markets,” proclaiming, “Successful designs depend greatly on the details of the market, including the culture and psychology of the participants” (Roth, 2015). One need not actually find an example of an economist counseling advisees to skip that additional course in game theory and take up cultural anthropology to arrive at the sense that matters had taken a surprising turn: only a decade before one regularly encountered brash claims that all social science worth its salt must be reducible to game theory, with market design cited as evidence for why this must be so (e.g., Binmore, 2004)."

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Here's the table of contents of the issue: