A typical metastable state of the homogeneous ferromagnetic Ising model with
Glauber dynamics on the 3-coordinated Cayley tree. At zero temperature these
metastable states are actually stable. Shown are the first 4 levels of the
tree. Spins in squares have their state uniquely determined by the states of
the two "daughter" spins (black for + spins, red for - spins). Spins in
circles are determined by the spin state of their parent (blue for + spins,
magenta for - spins).