A 15-year legacy
Simon Willerton drew these knots on a board at the University of Edinburgh when he was a graduate student in 1995, and today they are still there! You can see in the bottom left corner there is a message to new students that these knots must never be rubbed off, so there is every hope that they will persist for many years to come. Simon’s thesis was about Vassiliev invariants, which are a way of constructing knot invariants using the extended space of singular knots (i.e. not just the usual knots, like those drawn on the board, but knots which may intersect themselves or have crossings where more than two strands are present). It is still an open question in mathematics whether Vassiliev invariants can be used to distinguish any pair of knots.