Ferneyhough, Sheila2024-08-132024-08-1319961996https://hdl.handle.net/1828/17807The problem of determining choice numbers for unions of graphs is investigated, with particular attention being paid to the case where one of the graphs is 2-choosable. It is shown that all 2-choosable graphs are (2k k )-choosable for all positive values of k. New results on (a b)-choosability of planar graphs, bipartite graphs and Cartesian products of graphs are also presented.53 pagesAvailable to the World Wide WebThesis