Luitzen Egbertus Jan Brouwer (27 February 1881 – 2 December 1966) was a Dutch mathematician who founded intuitionism and made important contributions to topology, such as his fixed-point theorem, which states that every continuous function f mapping a compact convex set into itself has a fixed point a [i.e. f(a) = a]. A consequence of the theorem is when a crumpled sheet of paper is placed on top of (and within the boundaries of) a copy of itself, at least one point on the top sheet lies over the corresponding point on the bottom sheet.
The Dutch Royal Mathematical Society (Koninlijk Wiskundig Genootschap) is organising a special event marking 50 years since Brouwer’s death. The event is on 9 December in the Amsterdam Science Park. It looks to be an interesting event. Details here.