Soon-Mo Jung is a professor of mathematics at Hongik University in the Republic of Korea. His research interests include measure theory, number theory, and classical analysis. He received his bachelor's, master's, and doctoral degrees in 1988, 1992 and 1994, respectively, from the Department of Mathematics at the University of Stuttgart, Germany. One of the themes of his doctoral dissertation is closely related to the subject of this book, Ulam's conjecture. He has been a professor at Hongik University since 1995 and has published numerous papers and books in the fields of measure theory, fractal geometry, number theory, classical analysis, discrete mathematics, differential equations, and functional equations.