Popular Mechanics: “When you’re browsing online, who sets the prices? An algorithm, most likely. A study from 2015 showed that a third of all items on Amazon had prices set by an algorithm, and chances are that percentage has only risen. A new study shows how easy it would be for price-setting algorithms to learn to collude with each other and keep prices at a disadvantage for customers. This sort of collusion would stem from a certain type of algorithm, the researchers say. Reinforcement algorithms learn through trial and error. In the simplest terms, a walking robot would take a step, fall, and try again. These algorithms have often been used to teach algorithms to win games like Go.

“From the antitrust standpoint,” say professors Emilio Calvano, Giacomo Calzolari, and others from the University of Bologna in Italy, “the concern is that these autonomous pricing algorithms may independently discover that if they are to make the highest possible profit, they should avoid price wars. That is, they may learn to collude even if they have not been specifically instructed to do so, and even if they do not communicate with one another.” To test their theory they built two AI pricing agents and let them interact with each other. They found that “even relatively simple pricing algorithms systematically learn to play sophisticated collusive strategies.”..