Ulam has a result in measure theory the French mathematician LeCam called tightness. The result is in Patrick Billingsley, Convergence of Probability Measures

Ulam has a result in measure theory the French mathematician LeCam called tightness. The result is in Patrick Billingsley, Convergence of Probability Measures, John Wiley and Sons, New York, 1968. The result was used in a course I took in measure theory based probability theory. Later I used the result in one paper to show that a goofy statistical hypothesis test was not trivial. The URL I've had of the picture of Ulam, von Neumann, and Feynman at Los Alamos during WWII moved, but another copy is at https://3.bp.blogspot.com/-PRA6JxXrePw/Trm_LwKgxyI/AAAAAAAACh4/pNJwEHYwfxQ/s1600/StanislawUlamRichardFeynmanJohnVonNeumann.jpg https://3.bp.blogspot.com/-PRA6JxXrePw/Trm_LwKgxyI/AAAAAAAAC...