Title: On Bit Representations of Mixed-Integer Quadratic Programs.
Speaker: Prof. Adam Letchford
Affiliation: Management School – Lancaster University
Location: Room 217 Huxley Building
Time: 3:00pm (1 hour)

Abstract. A standard trick in integer programming is to replace each bounded general-integer variable with a small number of binary variables, using the bit representation of the given variable. (See, e.g., Owen & Mehrotra, 2002; Coppersmith & Lee, 2005; Muldoon et al., 2013; Bonami & Margot, 2015). Recently, bit representation was found to be useful for convexifying quadratic problems (Billionnet et al., 2012) and for linearising bilinear problems (Gupte et al., 2013). We show that,in the case of mixed-integer quadratic programs, bit representation has an additional benefit: it can enable one to obtain stronger linear programming relaxations.

About the speaker. Adam N. Letchford is known internationally for his research on exact solution methods for NP-hard optimisation problems. He has been the recipient of an IBM Faculty Award and an EPSRC Advanced Research Fellowship, and is a Fellow of the Operational Research Society. He has been on the editorial boards of six journals, including Mathematical Programming and Operations Research. From 2008-2014, he was the coordinator of the optimisation cluster of the LANCS Initiative. Since 2012, he has been the director of NATCOR, the UK National Taught Course Centre in Operational Research.