author    = {Martin Kronegger and Sebastian Ordyniak and Andreas Pfandler},
  title     = {Variable-Deletion Backdoors to Planning},
  booktitle = {Proc. of the 29th AAAI Conference on Artificial Intelligence (AAAI-15)},
  year      = {2015},
  pages     = {3305-3312},
  publisher = {AAAI Press},
  abstract  = {Backdoors are a powerful tool to obtain efficient algorithms for hard problems. Recently, two new notions of backdoors to planning were introduced. However, for one of the new notions (i.e., variable-deletion) only hardness results are known so far. In this work we improve the situation by defining a new type of variable-deletion backdoors based on the extended causal graph of a planning instance. For this notion of backdoors several fixed-parameter tractable algorithms are identified. Furthermore, we explore the capabilities of polynomial time preprocessing, i.e., we check whether there exists a polynomial kernel. Our results also show the close connection between planning and verification problems such as Vector Addition System with States (VASS).}