social networks formed by email, phone calls, instant messaging, etc., as well as various types of physical networks. Of particular interest to mathematicians is the collaboration graph, which is based on the data from Mathematical Reviews. In the collaboration graph, every mathematician is a vertex, and two mathematicians who wrote a joint paper are connected.” Chung's life was profiled in the 2017 documentary film Girls who fell in love with Math. In 2012, she became a fellow of the American Mathematical Society. Personal life Chung has two children; the first child was born during her graduate studies from her first marriage. Fan Chung's first marriage ended in divorce in 1982. However, when she worked at Bell Laboratories, she met Ronald Graham. During that time, they became close friends and published many joint papers in graph theory, eventually marrying in 1983. She was married to him until his death in 2020. In Paul Hoffman's book The Man Who Loved Only Numbers, regarding her marriage with Graham, Chung said: Many mathematicians would hate to marry someone in the profession. They fear their relationship would be too competitive. In our case, not only are we both mathematicians, we both do work in the same areas. So we can understand and appreciate what the other is working on, and we can work on things together and sometimes make good progress. Both Chung and Graham were close friends of the mathematician Paul Erdős, and have both published papers with him – 13 in her case; thus, both have Erdős numbers of one. In 1998, Graham and Chung co-wrote the book Erdős on Graphs. Research Chung has published more than 200 research papers and three books: Erdős on Graphs: His Legacy of Unsolved Problems (with Ron Graham), A K Peters, Ltd., 1998, Spectral Graph Theory (CBMS Regional Conference Series in Mathematics, No. 92), American Mathematical Society, 1997, Complex Graphs and Networks (CBMS Regional Conference Series in Mathematics, No. 107 " (with Linyuan Lu), American Mathematical Society, 2006, Spectral graph theory Among Fan Chung's publications, her contributions to spectral graph theory are important to this area of graph theory. From the first publications about undirected graphs to recent publications about directed graphs, Fan Chung creates the solid base in the spectral graph theory to the future graph theorist. Spectral graph theory, as one of the most important theories in graph theory, combines the algebra and graph perfectly.