01421nas a2200145 4500008004100000245010900041210006900150300001100219490000600230520095200236653002001188100001301208700001601221856003801237 2006 eng d00aIncreasing the efficiency of graph colouring algorithms with a representation based on vector operations0 aIncreasing the efficiency of graph colouring algorithms with a r a24--330 v13 aWe introduce a novel representation for the graph colouring problem, called the Integer Merge Model, which aims to reduce the time complexity of graph colouring algorithms. Moreover, this model provides useful information to aid in the creation of heuristics that can make the colouring process even faster. It also serves as a compact definition for the description of graph colouring algorithms. To verify the potential of the model, we use it in the complete algorithm DSATUR, and in two version of an incomplete approximation algorithm; an evolutionary algorithm and the same evolutionary algorithm extended with guiding heuristics. Both theoretical and empirical results are provided investigation is performed to show an increase in the efficiency of solving graph colouring problems. Two problem suites were used for the empirical evidence: a set of practical problem instances and a set of hard problem instances from the phase transition.10agraph colouring1 aJuhos, I1 aHemert, J I uhttp://research.nesc.ac.uk/node/7