Game Theory in Food Webs

While some applications of network theory may seem less than obvious (offensive strategy in basketball, for example), most of us are quite familiar with the idea that ecosystems can be represented as networks.  Cartoon illustrations of “food webs”, as Carl Zimmer notes in a recent Yale E360 article, are standard fare for kids’ science textbooks.  (What Zimmer doesn’t note is that they make great poster board-centric elementary school projects: my food web poster was killed at the science fair.)

In spite of the status of food webs as a matter of common knowledge, they have not been subjects of rigorous analysis until recently.  Zimmer points to the fact that, for decades, many biologists found detailed graphs of ecological networks to be too dense to be meaningfully analyzed.  This changed with the development of the kind of network theory that we’re now studying in this class.

For example, game theory helps explain the structure of networks of plants and pollinating insects and how this network encourages biodiversity.  These networks take the form of small-world networks; most species are connected to only a few other species in highly specialized ways, while a handful of species are connected to a large number of other species.  These “generalizers”, as Zimmer calls them, act as hubs that connect otherwise distant sections of the graph.

Most interesting, I think, is the game-theoretical side of these networks.  Zimmer gives an example of a generalizer moth that pollinates specialized plants. He notes that ecosystems are competitive, so it might seem natural to believe that a plant species would do better to have a dedicated, specialized pollinating insect, one that would not spend it’s efforts pollinating other plants.  This would appear to be a zero-sum game, with any pollination of other plant species happening at the expense of competing species.

The empirical data shows, however, that this tends not to be the case.  Specialized plants tend to pair with generalized insects and vice versa.  It might be more accurate to describe the game thusly: The Plant and the Moth both have two strategies, specialize and generalize.  If both specialize, they both receive the lowest payoff.  This is because the moth, being specialized, will have a limited food supply and therefore there will be a limited number of moths to pollinate the plant.  The plant will also have a limited number of moths to help it reproduce, limiting the number of plants and the moths’ food supply.  This limits the ability of either to flourish.  On the other hand, if either or both species generalize, they will both benefit greatly.  The species that generalizes will flourish (by merit of its ability to interact with more than one species), and the other species will receive the benefit of either greater food supply or greater reproductive capacity.  What is interesting here is that specialize-specialize is the only low payoff strategy, while all other combinations benefit both players significantly.


Google is Using the Network to Expand Personalization

Google Maps is the most interactive map ever created. It not only shows you state and street names, but it takes you to the street level and shows photos of what you were to see if you were at that geographical location on Earth. Instead of just names of restaurants, it shows their menus, contact info, and hours of operations. Google Maps has incorporated GPS and navigation into its software  and can tell you the best public transportation routes and times for many major global cities. In the meanwhile, Google has been amassing data as how each of us relate to our geographical and social networks. With invaluable amounts of data, Google is attempting to transform the data into usable information. Daniel Graf noted that the company has a lot in store for Google Maps for the next year in the article below. “There is a lot more you can do with a map. If you look at a map and if I look at a map, should it always be the same for you and me? I’m not sure about that, because I go to different places than you do.” Google in my opinion will connect us with bridges to nodes we would have never found before. With all basic uses of maps all but completed it will be “interesting” to see the things that can be done with a map and knowledge of our preferences and networks, and of our neighbors preferences and networks..

Yours Truly,

Suicide Terrorism and Game Theory

I stumbled upon this article on the recent work on Terrorism in Game Theory, and the section on Suicide Terrorism piqued my interest in particular. 

It’s easy to assume that suicide terrorism is not rational, and thus should not be analyzed in a regular game. This however, means that an individual does not understand the payoffs of most suicide terrorists. I recalled reading another article several years ago by Dr. Robert Pape called Dying to Win. Pape illustrates that suicide terror is in fact rational to many of the perpetrators, and that ideology and religion is far less of a motivator than commonly thought. As it turns out, suicide terror has a far higher success rate, and kills 12 times the people that a conventional attack does. Expected payoffs can include heightened prestige and camaraderie within the group before the attack, payments to the families of the perpetrator, rewards in the afterlife, or a sense of altruism gained by providing a sense of good to future generations. Even though it is difficult to image, “the terrorist views his or her anticipated marginal benefit as exceeding the associated marginal cost for all levels of resource expenditure, even that involving one’s life.” (Sandler, Siqueira)

It is because the terrorist values their resource expenditure, their life, so low compared to the payoffs, that effective counter-terrorism policies should not just be combating terrorists, but include the concept of improving the conditions in which likely terrorists thrive. It should be noted however, that while data is very hard to gather on suicide terrorists, we do know that they are usually not in poverty, many have a college degree, none are from a particular area, and most are not Muslim. (Pape) This means that targeted aid to regions deemed susceptible to suicide terror cannot be a single solution. So perhaps a better option is to strongly strike against the surviving families of suicide terror, to endanger the potential payoff. 

The article concludes 6 key points after their Game Theory Analysis of Suicide Terrorism. “First, suicide missions imply corner solutions where standard (marginal) policy interventions may be ineffective. Second, suicide terrorists tend to be well educated. Third, hardened targets are more apt to attract suicide bombers. Fourth, income assistance may not reduce suicide attacks, owing to opposing influences. Fifth, government must at times seek to give potential terrorist operatives those things provided by terrorist organizations—that is, a sense of social cohesion and social services. Sixth, terrorist organizations must circumvent a free-rider problem.” (Sandler, Siqueira)

What I take away from all this is that understanding the payoffs and motivators of seemingly irrational actors like terrorists can allow one to use extra tools to analyze their behavior, and an effective preventative or reactionary response. 

The Origin of the Dutch Auction

I had to read the book The Botany of Desire by Michael Pollan for a class last semester, so when we started talking about Dutch auctions and the flowers that started them, I knew immediately what flower we were talking about. This article reveals the origin of the Dutch auction; it began when traders from the Ottoman Empire brought tulip bulbs to Holland. Their novelty made them an instant favorite, and the demand for the bulbs grew quickly. However, it takes seven to twelve years for a tulip to grow from a seed to a tradable bulb, and tulip bulbs are only able to be dug up and moved in the summer months. In fact, one of the most coveted types of tulips was the Semper Augustus, which was desired for its coloration. This coloration was caused by a virus, which made this type of flower even more difficult to successfully cultivate. Therefore, demand was growing higher and higher while supply had to remain relatively constant, and this situation drove prices for the flowers extremely high.

The market for tulips led to multiple new financial developments. One of these was the Dutch auction. Marketplaces were overcrowded and disorganized, so the Dutch auction was invented to get traders in and out with what they wanted as quickly as possible and at a high price. The sellers would begin at a price at which they knew demand would be zero, and then lower the price at a known increment. Once a seller reached his internal price (which we know as the true value), the buyer would place a bid. Therefore, the bid was the price equivalent of a first-priced sealed-bid auction. This method was especially beneficial to the seller, who would always get the highest possible price for the bulb they were selling; on the other hand, the buyer would have to pay his maximum internal price, or his true value.

A New Cold War, in Cyberspace, Tests U.S. Ties to China

It’s something no one would have imagined; a war in cyberspace… The hacking groups were suspected to be located in the neighborhood in Shanghai, and they’ve stolen more than terabytes of data from American corporations. ( In someway so called “a new cold war” can be less dangerous, but in the other hand, this cyber-cold war have gotten worse and it’s so complex.

In the article it states that ” President Obama avoided mentioning China by name — or Russia or Iran, the other two countries the president worries most about — when he declared in his State of the Union address that “we know foreign countries and companies swipe our corporate secrets.” He added: “Now our enemies are also seeking the ability to sabotage our power grid, our financial institutions and our air traffic control systems.”

I don’t want to go too detail into politics, but this war needs a solution. The solution of the conservative wars are either agreements between the enemies or either one of the enemies win the battle. This is a new generations of war – new cold war – we are ought to be careful what the future/ the result of this holds.

NFL Auctions

Fans of the NFL probably are probably glad that in the last few years the league has changed its overtime rules slightly.

Under the old rules, the overtime period started with a coin toss. The winner of the coin toss would choose to receive a kick-off and try to score or kick-off and defend. The first team to score in the overtime period (touchdown or field goal) won the game. Unsurprisingly, coin toss winning teams did not choose to kick and defend. This means that the rules to overtime became win the coin toss, get the ball.  Because the overtime was sudden death, the team winning the coin toss and receiving only had to get enough yards to reach field goal range and kick a field goal. Winning the coin toss gave teams an advantage and the coin toss winning team won about 60% of games that went to overtime.

Under the new rules, both teams must be given possession of the ball. Unless the receiving team scores a touchdown, the kicking team will get a chance to play offense. After both teams have had the ball, it goes back to sudden death. While this is fairer, it still relies on a coin toss to decide who got the ball first.

In 2002, Chris Quanbeck, an engineer, came up with an even fairer, and definitely more interesting, solution: the coaches participate in an auction to determine possession and field position. The auctions use field position instead of money to determine “price”. Quanbeck lists three possible formats for the auction:

1. Similar to the Dutch auction, the price starts high and drops. In this case, the high price teams pay is starting with the ball at their own one yard line. The referee lowers the price (moves the ball away from the one yard line in one yard increments) until the a coach accepts the price (field position).

2. This auction is like the English auction. The starting price is excellent field position. A coach can either accept, in which case the other team gets the ball at the acceptance price, or they can increase the price (move the starting position farther and farther from the end zone).

3. The third auction is a sealed bid first price auction. The price they write down is the point on the field from which they are willing to take the ball and try to score. The team that selects the farthest yard line (highest price) will start with the ball there.

Of these three options I think the first one is the most exciting. Presumably coaches would go to the auction knowing what price they will accept, but there’s no way to know what the crowd noise and pressure will cause them to do. It would also be much more suspenseful for fans watching at home.

Game Theory at Work

The article “Gaming The System” gives a real life example of game theory at work. The article is about a programming course at Johns Hopkins university, and how the students used game theory to beat the grading system. The story goes that a class was scheduled to take a final, but decided to boycott the exam because of a loophole in the grading schematic. The loophole was that the instructors grading system was one that curved, the curve in this case was giving the highest score in the class an A and adjusting all the lower scores based on the highest one. So by all students boycotting the exam and receiving 0’s, they would all actually receive A’s. The decision for all students to boycott is a Nash equilibrium in that if all the students expected one another to boycott they would all receive the highest payoff of an A. Conversely the other Nash equilibrium was if the students believed that even one person would deviate from this strategy and take the test they would all decided to change their strategy and take the test. The strategy to boycott the test though is the dominant strategy in the fact that they would all get A’s. So they really had no reason to switch that strategy because there was a chance of a lower payoff if they took it, but not a higher one. 

Even more fascinating was the professors decisions to honor the curve and give all students A’s! He likely accepted that he got outsmarted, and thus honored the grade. But the article does say that he amended his syllabus to prevent being duped in the future. Non the less it was a fascinating real life example of game theory at work.