Leetsch C. Hsu (L. C. Hsu) — Chinese Mathematician and Educator

Research and main contributions

Hsu worked on problems in combinatorics, special functions and applied mathematics, often emphasizing concrete formulae and inversion techniques. One of his best-known collaborative results is the matrix inversion identity developed with the American mathematician Henry W. Gould, commonly referred to as the Gould–Hsu matrix inversion formula (published in the early 1970s). Such inversion formulae provide systematic ways to derive combinatorial identities, to invert relations between sequences, and to manipulate series and generating functions in discrete mathematics.

Selected contributions

• Gould–Hsu matrix inversion formula — a tool used in combinatorics and symbolic summation.
• Work connecting special functions and discrete identities, useful in both pure and applied contexts.
• Pedagogical and organizational efforts to develop applied mathematics programs.

Institutional role and teaching

Beyond research, Hsu played a major role in building mathematical capacity at several Chinese universities. He was a co‑founder of the Department of Mathematics at Jilin University and later established an Institute of Applied Mathematics and a research journal while at the Dalian University of Technology. Through these efforts he helped create formal structures for graduate training, collaborative research, and dissemination of mathematical work in mainland China.

Publications and editorial work

Hsu served as founder or editor of mathematical periodicals and encouraged applied and interdisciplinary investigations. His editorial activities complemented his research agenda by promoting methods that could be applied to problems in engineering, physics and computational science. Many of his papers concern explicit identities, inversion relations and techniques that remain useful tools in modern combinatorial analysis.

Legacy

Leetsch C. Hsu is remembered for combining rigorous mathematical work with institution building and teaching. His collaborations, most notably with Henry W. Gould, produced formulas that continue to appear in the literature on combinatorics and symbolic computation. He passed away in Beijing in March 2019 at the age of 98, leaving a legacy of research, students and organizations that advanced mathematical studies in China.