A Scalable Algorithm for Minimal Unsatisfiable Core Extraction
  We propose a new algorithm for minimal unsatisfiable core extraction, based on a deeper exploration of resolution-refutation properties. We provide experimental results on formal verification benchmarks confirming that our algorithm finds smaller cores than suboptimal algorithms; and that it runs faster than those algorithms that guarantee minimality of the core. 
Nachum Dershowitz, Ziyad Hanna and Alexander Nadel