  We consider the Emery model of a
  Cu-O plane of the high temperature superconductors. We show that in a
strong-coupling limit, with strong Coulomb repulsions between electrons on
nearest-neighbor O sites, the electron-dynamics is strictly one dimensional,
and consequently a number of asymptotically exact results can be obtained
concerning the electronic structure. In particular, we show that a nematic
phase, which spontaneously breaks the point- group symmetry of the square
lattice, is stable at low enough temperatures and strong enough coupling.
