We introduce some classical complexity-theoretic techniques to Parameterized Complexity. First, we study relativization for the machine models that were used by Chen, Flum, and Grohe (2005) to characterize a number of parameterized complexity classes. Here we obtain a new and nontrivial characterization of the A-Hierarchy in terms of oracle machines, and parameterize a famous result of Baker, Gill, and Solovay (1975), by proving that, relative to specific oracles, FPT and A[1] can either coincide or differ (a similar statement holds for FPT and W[P]). Second, we initiate the study of interactive proof systems in the parameterized setting, and show that every problem in the class AW[SAT] has a proof system with "short" interactions, in the sense that the number of rounds is upper-bounded in terms of the parameter value alone.

Interactive proofs, Parameterized complexity, Relativization
dx.doi.org/10.4230/LIPIcs.IPEC.2017.9
International Symposium on Parameterized and Exact Computation
Centrum Wiskunde & Informatica, Amsterdam, The Netherlands

Bottesch, R.C. (2017). Relativization and interactive proof systems in Parameterized Complexity theory. In Leibniz International Proceedings in Informatics. doi:10.4230/LIPIcs.IPEC.2017.9