TRAVELS: Formulated the Nikodym set in 1927 - a seemingly paradoxical result of a construction in measure theory. A Nikodym set in the unit square S in the Euclidean plane E2 is a subset N of S such that the area (i.e. two-dimensional Lebesgue measure) of N is 1, and for every point x of N, there is a straight line through x that meets N only at x. Of course!