Mathematicians and computer scientists study streams more or less independently from one another. Mathematicians are motivated by combinatorial problems that arise from number theory or probability. Computer scientists are motivated by infinite data types. These are separate fields, but the motivating question for both fields is the complexity of a symbolic representation, be it of a number or of a data stream. It is likely that methods from mathematics can be transferred to computer science and vice versa. The aim of the workshop is to establish such a transfer. Experts will provide survey talks on methods, main results and, most importantly, main open problems. These will be made as accessible as possible to non-experts. There will be ample time for participants to cooperate on these open problems, not necessarily solving them, but learning from each other's approach to these problems.