We consider the problem of aligned coloring of interval and chordal graphs. These problems have substantial applications to register allocation in compilers and have recently been proven NP-Hard. We provide the first constant approximations: a 4 3 -approximation for interval graphs and a 3 2 -approximation for chordal graphs. We extend our techniques to the problem of minimizing spillage in these graph types.
Douglas E. Carroll, Adam Meyerson, Brian Tagiku