Iterated Prisoner’s Dilemma

In class, we learned about the Prisoner’s dilemma as a starting topic of game theory. In this game the prisoners cannot communicate with each other and they independently choose between not confessing and confessing. The researchers Yuma Fujimotoa and Kunihiko Kaneko at the University of Tokyo take it one step further to study the iterated prisoner’s dilemma. In this version, the suspects both learn from the previous game to decide on the current game.

It was believed that both players usually will learn from previous games and this would result in no player being a victim. This research proves this wrong. According to the researchers, the result of this study is that exploitive behaviour always exists, and this exploitative behaviour is one that is stable. The exploitive behaviour is when the probability of not confessing is not the same between the suspects and this is since it is sometimes more beneficial to confess, and this exploits the other player.

basin structure and payoff matrices

The research has many ways that such exploitive behaviour exists and that it depends widely on the initial conditions of the game. One such behaviour is as follows. Assume the suspects are Alice and Bob and that Alice learns Bob’s strategy. Alice can ensure that Bob does not confess since it is a better outcome than them both confessing, and this way Alice is able to exploit. It was also seen that exploitation can go both ways between the players causing more complex outcomes.

It is a fascinating result and I believe that this will be helpful in better understanding some of the outcomes in real life since exploitation is seen common in society.

References:

https://www.technologyreview.com/s/613585/prisoners-dilemma-shows-how-exploitation-is-a-basic-property-of-human-society/

https://arxiv.org/pdf/1905.06602.pdf

Secrets of 2009-2010 FC Barcelona Team

FC Barcelona is a well known soccer club which plays in the Spanish League La Liga and during the 2009-2010 season they were unbeatable winning six major championships. You might wonder what their secret to success was during that season and if it is possible to analyze the aspects of their game better than existing methods. Can we analyze this using networks and concepts learnt in CSCC46? A recent study from Universidad Rey Juan Carlos proves that through using networks and analyzing it is possible to better understand the style of play.

First a network was created with nodes representing players in a particular game and an edge between each player existed if there was a pass between them at any time. The study also recorded the position of each player during the game. The network also contained a sliding window of 50 passes which will delete the very first edge as the game progresses and this helped in analysing different phases of the game.

What did this network reveal about the team? The network showed central team players through which the ball frequently passes through , triads between players who frequently passed the ball between each other and more. Calculating the clustering coefficient of this network concluded that Barcelona had one of best passing between neighbours of its players among all teams. It was also decided that Barcelona had the best shortest average paths which again shows the skill of passing across the team. The study also predicted probabilities of the team scoring a goal given a particular network.

Here is a graph that shows properties of the network from the study.

It is interesting how a network of a sports team can reveal a lot more about the style of a team and I wonder what the potential uses of it are in the future. Maybe opposing team coaches can use this information to better tackle a strong team or to use some of the techniques and strategies in their own team to improve.

Source: https://www.technologyreview.com/s/614440/network-science-reveals-the-secrets-of-the-worlds-best-soccer-team/