Just a month away from her 94th birthday, Ailsa Land passed away on May 16, 2021. Together with Alison Doig, she published pioneering work on branch-and-bound in Econometrica, work whose influence continues to this day. Indeed, according to Google Scholar, there have been close to 3900 citations to this Econometrica paper.
Ailsa spent her entire academic career at the London School of Economics (LSE), beginning as an undergraduate economics student and then progressing to graduate student, research assistant, lecturer, senior lecturer, reader, and then chaired professor. Notably she was the first woman professor of Operational Research in Britain. Her economics background and perspective informed her subsequent contributions to operations research, beginning with her 1956 dissertation on the application of OR techniques to the transportation of coking coal and extending to publications on a wide variety of applied problems (including international trade, manufacturing layout, machine scheduling, and sports analytics). It is noteworthy that the motivation for the development of the branch-and-bound technique came from her work on an applied economics problem for British Petroleum, involving the optimization of refinery operations when decision variables are necessarily discrete.
Her work on branch-and-bound led to developing the first successful computer codes for integer programming. Indeed, Ailsa was at the forefront of computational OR, in which well-tested computer code is implemented, taking into account both theoretical considerations and efficient data structures. A significant example of this effort was the 1973 book Fortran Codes for Mathematical Programming: Linear, Quadratic and Discrete, written jointly with her colleague Susan Powell. This work provided detailed documentation for computer implementations of optimization techniques as well as the underlying mathematical background and an accompanying suite of test problems.
In addition, Ailsa Land advanced OR methodology through publication of significant work on the traveling salesman problem, shortest path algorithms, quadratic programming, bicriteria decision problems, and statistical data fitting. After retirement from the LSE in 1987, she continued research projects, resulting in contributions to data envelopment analysis, combinatorial auctions, and the quadratic assignment problem. In 1994 she received the Harold Larnder Prize from the Canadian Operational Research Society for her contributions to mathematical programming. Quite recently she was awarded the 2019 Beale Medal from the British Operational Research Society.
Further information about her life and a fascinating 2019 interview can be found on the INFORMS History and Traditions website.
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Douglas Shier
Professor of Math Sciences, Emeritus
Clemson University
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