# Professor Johnny Henderson Retiring after 21 Years at Baylor

At the conclusion of this academic year, Distinguished Professor of Mathematics Johnny Henderson has retired after 21 years at Baylor. We are honored by his service to our department. His many contributions throughout the years have been a significant positive impact for our department and will be deeply missed.

Johnny was born on March 26, 1951, in Santa Monica, CA and grew up in Arkansas. He earned B.S. and M.S. degrees from the University of Arkansas in 1973 and 1975, respectively, before taking a teaching position at the University of Arkansas-Monticello. There he realized the immediate and profound impression that he could make on students through his teaching.

“I would sometimes visit the library and thumb through one of the few mathematics journals there and wonder how a person did the original research in those articles,” Henderson said. “I decided to attempt doctoral study in mathematics. I knew it would be a difficult journey, and I had no feel for its outcome.”

So, in 1977, he, his wife Darlene, and young daughter Kathy moved to the University of Nebraska to begin Ph.D. work. Although he had already learned under great teachers, at Nebraska he encountered several professors that would influence him the most in the years to come. For example, Johnny is famous for his research seminars used to train so many graduate students, but he credits an excellent mentor for teaching by example.

“Allan Peterson – who never left out a detail in his seminar lectures and who by example showed me how to be the coordinator of a seminar… I to this day try to emulate the Peterson style of seminar in my own seminars.”

Johnny completed his Ph.D. under Lloyd Jackson in 1981 and then took a faculty position at the University of Missouri-Rolla. In 1984, he moved to Auburn University serving as Alumni Endowed Chair for 5 years and later as the Scharnagel Endowed Professor. In 2002, Johnny moved to Baylor as Distinguished Professor to help develop a new Ph.D. program in mathematics.

Johnny’s research accomplishments have been incredibly profound. He is a prolific writer in differential equations and nonlinear analysis, having authored more than 600 refereed publications with 150 collaborators. More recently, he has turned to compiling his encyclopedic contributions into 12 extensive research monographs. His writing prominently displays his contributions across many subfields of mathematics, including functional differential equations, impulsive differential inclusions, fractional differential and integral equations, topological methods for differential inclusions, difference equations, and dynamic equations on time scales. His work has been cited more than 5100 times. In 2013, Johnny was selected in the first ever class of Fellows of the American Mathematical Society.

As expansive and impressive as his research accomplishments, Johnny may very well have made an even greater impact as a teacher over the years. He has directed 28 Ph.D. dissertations and 17 master’s theses and served on too many graduate committees to count. In 2001, he was awarded the Mathematical Association of America’s Southeastern Sectional Award for Distinguished College or University Teaching. In 2016, Johnny was named the Cornelia Marschall Smith Professor of the Year at Baylor with a prize of $20,000. As a fitting capstone to his career, Johnny won his second MAA teaching award with the 2023 Texas Sectional Award for Distinguished College or University Teaching.

With such research credentials and history of mentoring graduate students, it is easy to think that his transformative teaching has mainly been at the graduate level, but Johnny’s influence on generations of undergraduates may end up being even greater. Whether he is teaching a graduate course on boundary value problems or a sophomore level course on ordinary differential equations, his reputation precedes him: if you want a seat in one of his sections, you better register extremely early because his classes fill immediately. Year after year, students at all levels are quick to point to his humility, generosity of spirit, encouragement, and perhaps most importantly, his genuine care for each of them as individuals, regardless of where they are on their academic journey.

Former chair, Lance Littlejohn, who nominated Johnny for the Cornelia Marschall Smith Award, noted, “Johnny is adored by his students. As good as he is at research, and as impossible as this may sound, he just might be a better teacher,” Littlejohn said. “Students are his life blood. And Johnny does not say goodbye to his students at the end of a semester. In many cases, the end of the semester marks the beginning of a long-lasting relationship with his students; indeed, hundreds of Johnny’s students have stayed in touch with him long after they graduated from college.”

Johnny is well-known amongst his students for his dry humor, such as always choosing the seemingly random “52” whenever he needs a number or the value of a constant for an example. Everyone always looks around quizzically, “Why does he always pick 52? What’s special about 52?” (You’ll have to ask Johnny to find out.) Whenever he makes an error during lecture, he doesn’t shy away from it---often purposefully making them early in the semester, so he can tell them to pull out their giant erasers, which he calls Hershey bars due to their size and shape, and “We just Hershey bar out the mistake… it’ll all be ok!” This wit and reassuring charm have endeared him to generations of students. In fact, at the end of a recent semester, his differential equations class surprised Johnny by presenting him with the very purposefully personalized Baylor Bears jersey shown below!

Johnny’s impact both in research and teaching as well as service to the department, university, and mathematical community have been profound. We thank him for all that he has meant to us over the last 21 years and congratulate him on his retirement.

Quotes from Colleagues

Johnny has certainly been a tremendous, singular influence on me. I am so very thankful for his wise counsel. He has been a mentor and stalwart supporter in all aspects of my life: professionally, personally, and spiritually. Johnny and Darlene have known Tiffany and me since we were first married: they have been a second set of parents to us and grandparents to our children. We have celebrated joyous milestones in life together, but also endured painful losses together. For all those things, I am eternally grateful. Speaking for many generations of his students, we are honored to have been taught by Johnny Henderson! We celebrate his career and wish him the very best in whatever comes next.

--John Davis

Johnny played an instrumental role in launching the department’s Ph.D. program twenty years ago. He was hired because of his reputation as a well-published scholar and for his fit with Baylor’s mission. His impact in the mathematical community, both nationally and internationally, helped draw faculty and students to our department. At one point, half of the Ph.D. students in the department were Johnny’s students. Johnny not only excelled as a researcher, but he also earned national respect for his teaching, having won several major teaching awards. Students recognized his classroom abilities and literally flocked to his classes. I wish Johnny (and Darlene) all the best in his retirement and thank him for his dedication to the department. He helped lift our department into the national spotlight.

--Lance Littlejohn

Johnny has been a terrific colleague. For me this started in early 2016, even before I joined the department. From the very beginning, he was incredibly welcoming and supportive. While typically a quiet presence in our department, one could always count on his judgment in matters of importance. He perfectly understood when to make his point of view known. One of the most memorable interactions with him occurred very recently. After nearly 48 years as a member of the MAA, Johnny was notified that he had received the prestigious MAA Distinguished College or University Teaching of Mathematics Award from the Texas Section for 2023. It was quite a sight to see Johnny overjoyed and on cloud nine for a bit. What a wonderful honor to cap his distinguished career and his 21 years of impeccable service to Baylor. Johnny will most definitely be missed in our department.

--Fritz Gesztesy

Baylor Math has been so lucky to have Johnny Henderson. The students he taught loved him, so much so that careful control was needed to prevent everyone from signing up just for his classes. When he came to Baylor, he immediately started working on some graduate student issues, even though that was not his job. He took trips to Texas colleges to recruit students for our grad program, and he started talks by professors to let grad students know about our research (this later became the pizza seminar). And Johnny’s research has meant a great deal. His stature as a researcher and the amazing output of papers and books have buoyed the department. Johnny has been a great member of the department, often sharing cheer and good advice.

--Ron Morgan

Johnny has been an extremely knowledgeable, brilliant, humble, and productive mathematician and educator. In my memory, Johnny has never said “no” to anyone who was asking for help, no matter how busy he is. In fact, the only “no” I heard from him was after we flew together twice for conferences. Unexpectedly, both airplanes’ tires exploded. At that moment, Johnny looked at me and laughed: “No, perhaps I shouldn’t fly with you…” But of course, we flew together again, and there were no more incidents, indeed.

--Tim Sheng

Not only is Johnny Henderson a massively accomplished mathematician but he is a kind spirt, loved by all. I first crossed paths with Johnny when I was a graduate student at the University of South Carolina in 1993 while attending one of my first conferences in Wilmington, North Carolina. As luck would have it, Johnny was the chairman of the section in which I was scheduled to give my presentation. When I have eventually joined Baylor more than two decades later, Johnny remembered this brief encounter and gave me a copy of the program of the conference in Wilmington with our names on it as a welcome gift. I was deeply moved by his gesture.

--Marius Mitrea