Lorentz-invariant membranes and finite matrix approximations
  The question of Lorentz invariance for finite N approximations of relativistic membranes is addressed. We find that one of the classical manifestations of Lorentz-invariance is not possible for NxN matrices (at least when N=2 or 3). How the symmetry is restored in the large N limit is studied numerically. 
Jens Hoppe, Maciej Trzetrzelewski
hep-th