Another column reported on the discoveries made by University of Michigan professor Robert Axelrod in his computer tournament pitting many iterated prisoner's dilemma strategies against each other, and a follow-up column discussed a similar tournament that Hofstadter and his graduate student Marek Lugowski organized. The "Metamagical Themas" columns ranged over many themes, including patterns in Frédéric Chopin's piano music (particularly his études), the concept of superrationality (choosing to cooperate when the other party/adversary is assumed to be equally intelligent as oneself), and the self-modifying game of Nomic, based on the way in which the legal system modifies itself, and developed by philosopher Peter Suber. Hofstadter was married to Carol Ann Brush until her death. They met in Bloomington, and married in Ann Arbor in 1985. They had two children, Danny and Monica. Carol died in 1993 from the sudden onset of a brain tumor—glioblastoma multiforme—when their children were five and two. The Carol Ann Brush Hofstadter Memorial Scholarship for Bologna-bound Indiana University students was established in 1996 in her name. Hofstadter's book "Le Ton beau de Marot" is dedicated to their two children and its dedication reads "To M. & D., living sparks of their Mommy's soul". In the fall of 2010, Hofstadter met Baofen Lin in a chacha class, and they married in Bloomington in September 2012. Hofstadter has composed numerous pieces for piano, and a few for piano and voice. He created an audio CD, "DRH/JJ", which includes all these compositions performed mostly by pianist Jane Jackson, with a few performed by Brian Jones, Dafna Barenboim, Gitanjali Mathur and Hofstadter. The dedication for "I Am A Strange Loop" is: "To my sister Laura, who can understand, and to our sister Molly, who cannot." Hofstadter explains in the preface that his younger sister Molly never developed the ability to speak or understand language. As a consequence of his attitudes about consciousness and empathy, Hofstadter has been a vegan for roughly half his life. In the 1982 novel "", Arthur C. Clarke's first sequel to "", HAL 9000 is described by Dr. Chandra as being caught in a "Hofstadter–Möbius loop". The movie uses the term "H. Möbius loop".