Vertex 2-coloring without monochromatic cycles
  In this paper we study a problem of vertex two-coloring of undirected graph such that there is no monochromatic cycle of given length. We show that this problem is hard to solve. We give a proof by presenting a reduction from variation of satisfiability (SAT) problem. We show nice properties of coloring cliques with two colors which plays pivotal role in the reduction construction. 
Micha{\l} Karpi\'nski
cs.CC cs.DS