Preface

This special issue celebrates the 75th birthday of Professor Michael Klibanov, honoring his exceptional contributions to inverse problems, ill-posed problems, and mathematical science.Over the decades, Professor Klibanov's work has had a transformative impact, introducing novel approaches that have significantly advanced our understanding in these challenging areas.In 1981, in collaboration with Alexander Bukhgeim, Professor Klibanov introduced the Bukhgeim-Klibanov method-a powerful and influential technique for multidimensional coefficient inverse problems (CIPs).This method has become central to the field, enabling global uniqueness proofs and stability results for a broad class of CIPs.Beyond his foundational theoretical work, Professor Klibanov has developed globally convergent numerical methods, most notably the convexification method, which have been successfully tested on real experimental data.In recent years, he has also made notable contributions to the theory of mean field games (MFG), opening new interdisciplinary directions at the intersection of mathematics, economics, and game theory.This issue brings together contributions from Professor Klibanov's colleagues, collaborators, and students, reflecting the wide-ranging impact of his work.As we celebrate this milestone, we recognize not only the depth of his intellectual legacy but also the enduring influence of his research across mathematics and beyond.