Viorel Nitica died at home on Sunday, June 20, 2021, after a 40-month battle with brain cancer. Viorel Nitica grew up in Romania and earned his bachelor's and master's degrees in mathematics at the University of Bucharest He earned his doctoral degree in mathematics in 1995 at Penn State University under the guidance of Anatole Katok, a world-renowned mathematician and one of the most influential figures in his field of dynamical systems. The monograph he co-authored with Katok was the first publication of this sort to present the modern advances in the rigidity of higher-rank Abelian group actions, a field to which Viorel himself has made many contributions.
Viorel's research extended to many areas of mathematics, including operator algebras, dynamical systems, geometry of max-plus spaces, topological groups and Lie groups, tilings and combinatorics, and number theory. Four sequences are attributed to him in the "Online Encyclopedia of Integer Sequences." His interests led to collaborations at many universities in various countries around the world. Viorel also held positions at the University of Notre Dame and Indiana University at Bloomington, as well as teaching summer school for advanced students at Penn State University.
Viorel was a member of the American Mathematical Society and the Institute of Mathematics of Romanian Academy. Additionally, he served on editorial committees of mathematical journals. Over the years he won several grants from prestigious institutions such as the National Science Foundation and the Simons Foundation, and awards, such as the 2012 West Chester University Trustee's Achievement Award. He was known for his passion of knowledge and research and being an excellent teacher who cared about the success of his students, many of whom fondly appreciated his mentorship. Viorel was generous collaborator and a valued colleague who will be greatly missed.