Charles R. Johnson is Class of 1961 Professor of Mathematics at the College of William and Mary, Virginia. He is the recognized expert in the interplay between linear algebra and combinatorics, as well as many parts of matrix analysis. He is coauthor of Matrix Analysis (Cambridge, 2012), Topics in Matrix Analysis (Cambridge, 2010), both with Roger Horn, and Totally Nonnegative Matrices (2011, with Shaun Fallat). Carlos M. Saiago is Assistant Professor of Mathematics at Universidade Nova de Lisboa, Portugal, and is the author of fifteen papers on eigenvalues, multiplicities, and graphs.

'The authors offer a unique and modern exploration into the eigenvalues associated with a graph, well beyond the classical treatments. This well-written and comprehensive monograph is ideal for newcomers to this subject and will be beneficial for experienced practitioners as well.' Shaun M. Fallat, University of Regina, Canada

• Background; 1. Introduction; 2. Parter-Wiener, etc. theory; 3. Maximum multiplicity for trees, I; 4. Multiple eigenvalues and structure; 5. Maximum multiplicity, II; 6. The minimum number of distinct eigenvalues; 7. Construction techniques; 8. Multiplicity lists for generalized stars; 9. Double generalized stars; 10. Linear trees; 11. Non-trees; 12. Geometric multiplicities for general matrices over a field.