This volume is dedicated to Bill Helton on the occasion of his sixty fifth birthday. It contains biographical material, a list of Bill's publications, a detailed survey of Bill's contributions to operator theory, optimization and control and 19 technical articles. Most of the technical articles are expository and should serve as useful introductions to many of the areas which Bill's highly original contributions have helped to shape over the last forty odd years. These include interpolation, Szegö limit theorems, Nehari problems, trace formulas, systems and control theory, convexity, matrix completion problems, linear matrix inequalities and optimization.

The book should be useful to graduate students in mathematics and engineering, as well as to faculty and individuals seeking entry level introductions and references to the indicated topics. It can also serve as a supplementary text to numerous courses in pure and applied  mathematics and engineering, as well as a source book for seminars.

The Festschrift in celebration of John William Helton's pioneering work, Mathematical Methods in Systems, Optimization, and Control comprises a careful selection of articles on systems and control theory, operator theory, and optimization. The book follows Helton’s original and long lasting contributions which have shaped control theory and operator theory during the last decades, with specific emphasis on topics aimed at direct applications to current research areas of high impact and interest.

The book, by virtue of its diverse contents, strong interdisciplinary contents, and high expertise of its contributors, is one of a kind among all recent publications in the area of mathematical control theory. Mathematicians of all denominations (algebraists, geometers, analysts, numerical and computer scientists) as well as engineers interested in control and optimization will find invaluable references and sources of inspiration in the book.