Professor Adam Letchford

Professor of Analytics and Optimisation

Research Overview

My research is in optimisation, i.e., finding the best solution to problems that have a huge (possibly infinite) number of solutions. Optimisation is an inter-disciplinary subject, lying at the interface between Operational Research, Computer Science, Applied Mathematics and Engineering. I concentrate mainly on methods for solving optimisation problems to proven optimality, rather than heuristic methods. I have a particular interest in combinatorial optimisation problems, i.e., problems in which variables are restricted to take integer (whole-number) values.

Selected Publications Show all 172 publications

Ellipsoidal relaxations of the stable set problem: theory and algorithms
Giandomenico, M., Letchford, A., Rossi, F., Smriglio, S. 1/08/2015 In: SIAM Journal on Optimization. 25, 3, p. 1944-1963. 20 p.
Journal article

Cutting planes for RLT relaxations of mixed 0-1 polynomial programs
Djeumou Fomeni, F., Kaparis, K., Letchford, A. 23/01/2015 In: Mathematical Programming. 151, 2, p. 639–658. 20 p.
Journal article

Stronger multi-commodity flow formulations of the capacitated vehicle routing problem
Letchford, A., Salazar Gonzalez, J.J. 1/08/2015 In: European Journal of Operational Research. 244, 3, p. 730-738. 9 p.
Journal article

The Steiner travelling salesman problem with correlated costs
Letchford, A., Nasiri, S. 16/08/2015 In: European Journal of Operational Research. 245, 1, p. 62–69. 8 p.
Journal article

Stronger multi-commodity flow formulations of the (capacitated) sequential ordering problem
Letchford, A., Salazar Gonzalez, J.J. 16/05/2016 In: European Journal of Operational Research. 251, 1, p. 74-84. 11 p.
Journal article

Pricing routines for vehicle routing with time windows on road networks
Letchford, A., Nasiri, S.D., Oukil, A. 11/2014 In: Computers and Operations Research. 51, p. 331-337. 7 p.
Journal article

A dynamic programming heuristic for the quadratic knapsack problem
Djeumou Fomeni, F., Letchford, A. 02/2014 In: INFORMS Journal on Computing. 26, 1, p. 173-182. 10 p.
Journal article

An aggressive reduction scheme for the simple plant location problem
Letchford, A., Miller, S. 1/05/2014 In: European Journal of Operational Research. 234, 3, p. 674-682. 9 p.
Journal article

23rd International Symposium on Mathematical Programming
Participation in conference

International Symposium on Combinatorial Optimization
Participation in conference

International Symposium on Combinatorial Optimization
Participation in conference

23rd International Symposium on Mathematical Programming
Participation in conference

1st Joint IMA/ORS Conference
Participation in conference

Bit representations of mixed-integer quadratic programs
Invited talk

International Symposium on Combinatorial Optimisation
Participation in conference

International Symposium on Combinatorial Optimization
Participation in conference

International Symposium on Combinatorial Optimisation
Participation in conference

An introduction to approximation algorithms (and inapproximability)
Invited talk

Mathematical Programming (Journal)
Editorial activity

Stronger multi-commodity flow formulations of the capacitated vehicle routing problem
Invited talk

Some unbounded convex sets arising in non-convex MIQP
Invited talk

Strengthening the reformulation-linearisation technique with cutting planes
Invited talk

Second order cone programming and its applications
Invited talk

European Conference on Operational Research
Participation in conference

International Symposium on Mathematical Programming
Participation in conference

EURO Journal on Computational Optimization (Journal)
Editorial activity

Operations Research (Journal)
Editorial activity

Applied Mathematical Optimization and Modelling
Participation in conference

International Symposium on Combinatorial Optimisation
Participation in conference

Reformulating mixed-integer quadratically-constrained quadratic programmes
Invited talk

Convex relaxations of the stable set problem
Invited talk

A tutorial on mixed-integer non-linear programming
Invited talk

Mixed-integer non-linear programming: a survey
Invited talk

Reformulation of 0-1 quadratically constrained quadratic programs
Invited talk

An introduction to second-order cone programming
Invited talk

London School of Economics
Visiting an external academic institution

Optimisation over cones
Invited talk

The Travelling Salesman Problem
Invited talk

European Chapter on Combinatorial Optimization
Participation in conference

Algorithmic Aspects in Information and Management
Participation in conference

Fifty years of cutting planes
Invited talk

On non-convex quadratic programming with box constraints
Invited talk

Recent progress on knapsack-based cutting planes
Invited talk

EURO XXIII - 23rd European Conference on Operational Research
Participation in conference

UK Operational Research Society Conference
Participation in conference

Discrete Optimization (Journal)
Editorial activity

International Network Optimization Conference
Participation in conference

Binary positive semidefinite matrices and some related polytopes
Invited talk

Discrete Applied Mathematics (Journal)
Editorial activity

International Symposium on Combinatorial Optimisation
Participation in conference

INFORMS Optimization Society
Participation in conference

Mathematical Programming Computation (Journal)
Editorial activity

ALIO/EURO Conference on Combinatorial Optimization
Participation in conference

An introduction to conic programming
Invited talk

Stronger upper bounds for the maximum stable set problem
Invited talk

Discrete Optimization (Journal)
Editorial activity

Semidefinite programming and combinatorial optimization
Invited talk

Algorithms for planar graphs
Invited talk

Vehicle routing games
Invited talk

Planar graphs and the traveling salesman problem
Invited talk

Solving discrete optimization problems by branch-and-cut
Invited talk

Vehicle routing games
Invited talk

Computational Optimization and Applications (Journal)
Editorial activity

Exploring the relationship between max-cut and stable set relaxations
Invited talk

The traveling salesman problem: inequalities and separation
Invited talk

The traveling salesman problem: inequalities and separation
Invited talk

Solving discrete optimization problems by branch-and-cut
Invited talk

The traveling salesman problem: inequalities and separation
Invited talk

The traveling salesman problem: inequalities and separation
Invited talk

Solving discrete optimization problems by branch-and-cut
Invited talk

Solving discrete optimisation problems by branch-and-cut
Invited talk

On traveling salesman games
Invited talk

Mathematical Programming (Journal)
Editorial activity

Primal separation algorithms
Invited talk

Associazione Italiana di Ricerca Operativa (External organisation)
Member of an organisation

The Operational Research Society (External organisation)
Member of an organisation

Fellow of the Operational Research Society (FORS)
Fellowship awarded competitively

Recipient of IBM Faculty Award
Prize (including medals and awards)

  • Centre for Transportation Systems & Logistics (CENTRAL)
  • Optimisation
  • STOR-i Centre for Doctoral Training