One of the problems with a classic Turing machine is the tape must be infinitely long. [Mark’s] Turing Ring still doesn’t have an infinite tape, but it does make it circular to save space. That along ...

Once upon a time, over 40 years ago, a horde of computer scientists descended on the West German city of Dortmund. They were competing to catch an elusive quarry — only four of its kind had ever been ...