Colleagues recall that Fejér could look at a sequence of polynomials and, almost by instinct, identify the precise inequality that governed their growth. "He saw through the notation," said Dr. Anna Kovács, a former student now at the University of Vienna. "Most of us compute. Béla listened to what the function was trying to say." If the archival record shows Fejér’s genius, the memories of his students reveal his humanity. From 1970 until his retirement in 2005, Fejér held the Chair of Analysis at the Bolyai Institute in Szeged, followed by a long tenure at the Alfréd Rényi Institute of Mathematics in Budapest.
Fejér’s students remember his patience but also his high standards. He famously told a PhD candidate who had submitted a 150-page thesis: "You have written 150 pages to avoid writing one clear idea. Go back. Find the one idea." The student returned with 15 pages and earned his doctorate summa cum laude. Outside of mathematics, Béla Fejér lived a quiet, almost monastic life. He was an avid walker in the Buda hills, often disappearing for hours with a notebook that he claimed was for "bird watching," though colleagues suspected he was solving functional equations in his head. bela fejer obituary
His 1978 paper, "On the Location of Zeros and the Fejér–Riesz Factorization," is considered a masterpiece. In it, he extended the classical theory of orthogonal polynomials to what are now known as "Fejér kernels" in weighted Lp spaces. For the working analyst, the Fejér kernel is a tool of staggering utility—a method of summing Fourier series that avoids the nasty oscillations (the Gibbs phenomenon) that plague other methods. Colleagues recall that Fejér could look at a
He is survived by his sister, Klára, his former students scattered across the globe, and a body of work that stands as a monument to the Hungarian spirit of mathematical inquiry. "Most of us compute
Yet friends note that his proudest moment was not a prize but a 2001 conference in his honor, "FejérFest," held at the Rényi Institute. When presented with a Festschrift—a celebratory volume of research papers—he wept quietly, saying only, "They read me. They actually read me." In his final decade, Fejér’s output slowed but never stopped. Even at 85, he was publishing notes in the Journal of Approximation Theory , refining results that graduate students still struggle to prove. His last paper, published in 2022, was a two-page note that resolved a 40-year-old conjecture about the Landau–Kolmogorov inequalities. It was characteristically terse, elegant, and devastatingly correct.
He was married once, to Erzsébet (Éva) Fejér, a linguist and translator. Theirs was a partnership of parallel solitude: she translated French poetry while he sketched inequalities. Éva predeceased him in 2015. They had no children. When asked why, Fejér reportedly replied, "I have thousands of children. They are called polynomials, and they behave better than humans."
There is a story often told at Hungarian mathematics conferences. A student once asked Fejér, "Professor, what is the most important inequality in mathematics?" Without hesitation, Fejér replied, "The one you don't know yet."