Andrew Mathas University of Sydney Rouquier blocks of symmetric groups Friday 14th May, 12:05-12:55pm, Carslaw 373. One of the classic unsolved questions in modular representation theory asks if we can compute the decomposition numbers of the symmetric groups in positive characteristic. That is, can we describe how the ordinary irreducible representations "break up" when we reduce them modulo some prime? The answer to this question in general is still far out of reach; however, for a distinguished class of blocks - the Rouquier blocks - this problem has been solved completely by Leclerc and Miyachi, and by Chuang and Tan, independently (generalizing earlier work of James and Mathas). This talk will be a survey of these results.