id: 06034526 dt: j an: 06034526 au: Zhai, Mingqing; Lin, Huiqiu; Wang, Bing ti: Sharp upper bounds on the second largest eigenvalues of connected graphs. so: Linear Algebra Appl. 437, No. 1, 236-241 (2012). py: 2012 pu: Elsevier Science Inc. (North-Holland), New York, NY la: EN cc: ut: bipartite graph; the second largest eigenvalue ci: Zbl 0666.05056 li: doi:10.1016/j.laa.2012.02.004 ab: Summary: Let $λ_{2}$ be the second largest eigenvalue of a graph. {\it D. I. Powers} [Linear Algebra Appl. 101, 121‒133 (1988; Zbl 0666.05056)] gave some upper bounds of $λ_{2}$ for general graphs and bipartite graphs, respectively. Considering that these bounds are not always attainable for connected graphs, we present sharp upper bounds of $λ_{2}$ for connected graphs and connected bipartite graphs in this paper. Moreover, the extremal graphs are completely characterized. rv: