In addition to creating vivid virtual worlds we can enter and fictional characters we can interact with, researchers are also developing complex computer models of plot. For instance, at Carnegie Mellon university, the Oz group, led by Joseph Bates, applies artificial intelligence techniques to storytelling. [...] The Oz group analysed all of the possible paths a player may take through the story and identified the ones that are the most satisfying. Then they fed this information to a complex mathematical procedure called "adversary search", which is similar to the algorithms used in chess-playing systems, and which can calculate the optimal response to any action of the player toward the most interesting narrative paths.