The strong chromatic number of a graph. Acyclic coloring of graphs. Transversal numbers of uniform hypergraphs. Combinatorial reconstruction problems. Ramsey graphs cannot be defined by real polynomials.
Ramsey graphs contain many distinct induced subgraphs.
The maximum number of Hamiltonian paths in tournaments. A separator theorem for nonplanar graphs. Universal sequences for complete graphs. Not all graphs are segment T -graphs. European J. Combin.