Frustration from Simultaneous Updating in Sznajd Consensus Model
  In the Sznajd model of 2000, a pair of neighbouring agents on a square lattice convinces its six neighbours of the pair opinion iff the two agents of the pair share the same opinion. Now we replace the usual random sequential updating rule by simultaneous updating and find that this change makes a complete consenus much more difficult. The larger the lattice is, the higher must be the initial majority for one of the two competing opinions to become the consensus. 
Dietrich Stauffer