P. Gopalan, P. G. Kolaitis, E. N. Maneva and C. H. Papadimitriou studied in [Gopalan et al., ICALP2006] connectivity properties of the solution-space of Boolean formulas, and investigated complexity issues on connectivity problems in Schaefer's framework [Schaefer, STOC1978]. A set S of logical relations is Schaefer if all relations in ... more >>>