Erusalimskij, Ya. M.; Natanzon, L. V. Graphs of bridges, blocks and cutpoints. Graphs of bibridges, biblocks and bicutpoints. (Russian) Zbl 1016.05048 Izv. Vyssh. Uchebn. Zaved., Sev.-Kavk. Reg., Estestv. Nauki 1998, No. 4, 30-35 (1998). Factorizations of oriented graphs of bibridges, biblocks, and bicutpoints are introduced and combinatorial relations are presented: an equality which enables to determine the number of graph blocks on the information about the number of cutpoints and a sum of defect numbers of cutpoints; an inequalities which enables to evaluate positive and negative half-powers and powers of biblock nodes, and an inequality which relates the number of nodes to the number of edges. Reviewer: Andrei Zemskov (Moskva) MSC: 05C38 Paths and cycles 05C20 Directed graphs (digraphs), tournaments 05C75 Structural characterization of families of graphs Keywords:graphs; blocks; bridges; nodes; combinatorics; factorization; oriented graphs PDFBibTeX XMLCite \textit{Ya. M. Erusalimskij} and \textit{L. V. Natanzon}, Izv. Vyssh. Uchebn. Zaved., Sev.-Kavk. Reg., Estestv. Nauki 1998, No. 4, 30--35 (1998; Zbl 1016.05048)