Ailsa Land


Ailsa H. Land is an Emeritus Professor of Operational Research in the Department of Management at the London School of Economics. She is most well-known for co-defining the branch and bound algorithm along with Alison Doig whilst carrying out research at the London School of Economics in 1960. She is married to Frank Land who is also an Emeritus Professor at the LSE.

Education

Land obtained her PhD from the London School of Economics in 1956, her dissertation was entitled An Application of the Techniques of Linear Programming to the Transportation of Coal, supervised by George Morton.

Integer programming

Land worked with Helen Makower, Alison Doig and George Morton in the late 1950s on a number of integer programming problems such as the travelling salesman problem and aircraft scheduling. However these were seemingly too complex to solve.
British Petroleum commissioned Land and Doig to investigate using discrete variables within linear programming models. Through this investigation they developed the branch and bound algorithm for solving integer problems. This solution method is now the most prevalent solution method for NP-hard optimisation problems.
Land implemented her linear and integer programming algorithms in Fortran. Later, with Susan Powell, she collected her implementations in a book, Fortran Codes for Mathematical Programming: Linear, Quadratic and Discrete.

Awards and honours

Land was awarded with the Harold Larnder prize by the Canadian Operational Research Society in 1994 for achieving international distinction in operational research.
A student award at the London School of Economics, the Ailsa Land Prize, is given annually in her honour.