Binary Decision Diagram Algorithms to Perform Hard Analysis Operations on Variability Models - Ruben Heradio; Hector Perez-Morago; David Fernandez-Amoros; Roberto Bean; F. Javier Cabrerizo; Carlos Cerrada; Enrique Herrera-Viedma (THE 15TH INTERNATIONAL CONFERENCE ON INTELLIGENT SOFTWARE METHODOLOGIES, TOOLS, AND TECHNIQUES (SOMET 16), 2016)