Ljiljana Brankovic Henning Fernau Joachim Kneis Dieter Kratsch Alexander Langer Mathieu Liedloff Daniel Raible Peter Rossmanith Breaking the 2^n-Barrier for Irredundance: A Parameterized Route to Solving Exact Puzzles http://arxiv.org/abs/0909.4224 2009 CoRR abs/0909.4224 db/journals/corr/corr0909.html#abs-0909-4224 informal publication