  Parker's formulation of isotopological plasma relaxation process toward
minimum magnetics energy states in magnetohydrodynamics (MHD) is extended to
electron MHD (EMHD).
  The lower bound on magnetic energy in EMHD is determined by both the magnetic
field and the electron vorticity field topologies, and is shown to be reduced
further in EMHD by an amount proportional to the sum of total electron-flow
kinetic energy and total electron-flow enstrophy. The EMHD Beltrami condition
becomes equivalent to the potential vorticity conservation equation in
two-dimensional (2D) hydrodynamics, and the torsion coefficient and turns out
to be proportional to potential vorticity. The winding pattern of the magnetic
field lines appears to evolve therefore in the same way as "potential
vorticity" lines in 2D hydrodynamics.
