Leonardo Vanneschi Sébastien Vérel Marco Tomassini Philippe Collard NK Landscapes Difficulty and Negative Slope Coefficient: How Sampling Influences the Results. 645-654 2009 EvoWorkshops http://dx.doi.org/10.1007/978-3-642-01129-0_74 conf/evoW/2009 db/conf/evoW/evoW2009.html#VanneschiVTC09