On two problems of the graph theory
On varieties of graphs
In this paper, we introduce the notion of a variety of graphs closed under isomorphic images, subgraph identifications and induced subgraphs (induced connected subgraphs) firstly and next closed under isomorphic images, subgraph identifications, circuits and cliques. The structure of the corresponding lattices is investigated.
On weak direct product decompositions of lattices and graphs
Ordres "C.A.C."
Orientations of graphs minimizing the radius or the diameter