
 IMA 2004 Summer Program: nCategories: Foundations and Applications, June 718, 2004 (Site not responding. Last check: 20071022) 
  Their focus was not on categories and functors, but on natural transformations, which are maps between functors. 
  In contrast to the introduction of categories, functors, and natural transformations, which could successfully be carried out by two authors in one paper, the development of higher category theory is technically very difficult mathematics. 
  We hope to develop a clear language of higher category theory that, like the original language of categories, functors, and natural transformations, can be accepted, understood, and worked with by mathematicians in general, whether algebraic geometers, logicians, algebraic topologists, mathematical physicists, or theoretical computer scientists. 
 www.ima.umn.edu /categories (612 words) 
