講題：Kelmans transformations for digraphs
講者：翁志文教授 (國立交通大學 應用數學系)
時間：107年10月25日(星期四)下午13:30-15:00
地點：民生校區五育樓4樓401教室
摘要
Let G denote an undirected graph with two vertices u, v. The Kelmans transformation of G from u to v is the graph G(u, v) which has the same vertex set of G and replace edge uw by vw for each w in N(u)-N[v].
It is well known that \rho(G)<= \rho(G(u, v)), where \rho(G) denotes the maximum real eigenvalue of G. In this talk we begin with a proof of the above inequality. Motivated by this proof, we introduce a related transformation on directed graphs which possesses of a similar inequality.