"Often we have a working group on research problems. Each summer since 2004 this has taken the form of a REGS group (Research Experiences for Graduate Students) supported initially by our department's VIGRE grant, subsequently by departmental funding, and later by our MCTP grant. The grant has now ended, so for the present the REGS program will not continue on a formal basis.
Our weekly seminars include Graph theory and Combinatorics and Algebra-Geometry-Combinatorics. Weekly details are found in the Mathematics Department seminar schedule. Seminars in theoretical computer science in the Computer Science Department also often discuss topics in discrete mathematics." from Combinatorics at the University of Illinois at Urbana-Champaign, Department of Mathematics, University of Illinois at Urbana-Champaign
Books on combinatorics and optimization can be found in the Mathemathics Library Stacks shelved under call number ranges 511.6 and 519.6, respectively.