Open Problems for Undergraduates - A collection of open problems in Discrete Mathematics which are currently being researched by members of the DIMACS community.
Past Open Problems - From the SIAM Activity Group Newsletter in Discrete Mathematics. In PostScript. Compiled by Douglas B. West.
Problems in Graph Theory and Combinatorics - A collection maintained by Douglas B. West, of the University of Illinois. Features brief introductions, along with references cited. Topics include matching and independence, connectivity, graph homomorphism and circular coloring.
Some Problems in Matroid Theory - Thomas Zaslavsky of Binghamton State University of New York presents brief descriptions and references. Find information on Bonin's Projective Bound including the maximum r-flat, covering and packing by flats.