Reoptimization of Parameterized Problems

Parameterized complexity allows us to analyze the time complexity of problems with respect to a natural parameter depending on the problem. Reoptimization looks for solutions or approximations for problem instances when given solutions to neighboring instances. We try to combine both techniques, in order to better classify the complexity of problems in the parameterized setting. Specifically, we see that some problems in the class of compositional problems, which do not have polynomial kernels under standard complexity-theoretic assumptions, do have polynomial kernels under reoptimization for some local modifications. Moreover, we find that the reoptimization version of Vertex Cover has a polynomial kernel of size 2k using crown decomposition. Finally, in a negative result, we prove that the reoptimization version of Connected Vertex Cover does not have a Turing kernelization unless Set Cover has a polynomial kernel