Evolving difficult SAT instances thanks to local search

We propose to use local search algorithms to produce SAT instances which are harder to solve than randomly generated k-CNF formulae. The first results, obtained with rudimentary search algorithms, show that the approach deserves further study. It could be used as a test of robustness for SAT solvers, and could help to investigate how branching heuristics, learning strategies, and other aspects of solvers impact there robustness.