A Heuristic for Magic and Antimagic Graph Labellings

Graph labellings have been a very fruitful area of research in the last four decades. However, despite the staggering number of papers published in the field (over 1000), few general results are available, and most papers deal with particular classes of graphs and methods. Here we approach the problem from the computational viewpoint, and in a quite general way. We present the existence problem of a particular labelling as a combinatorial optimization problem, then we discuss the possible strategies to solve it, and finally we present a heuristic for finding different classes of labellings, like vertex-, edge-, or face-magic, and (a, d)antimagic (v, e, f)-labellings. The algorithm has been implemented in C++ and MATLAB, and with its aid we have been able to derive new results for some classes of graphs, in ∗Work done while visiting the University of Newcastle, Australia †Also University of West Bohemia, Czech Republic, and Kings College, London, UK ‡Work done while visiting the University of Newcastle, Australia §Work done while visiting the University Jaume I, Castellon, Spain particular, vertex-antimagic edge labellings for small graphs of the type P r 2 × P s 3 , for which no general construction is known so far.