  The particle-particle hole-hole ring-diagram summation method is employed to
obtain the equation of state of asymmetric nuclear matter over a wide range of
asymmetry fraction. Compared with Brueckner Hartree-Fock and model-space
Brueckner Hartree-Fock calculations, this approach gives a softer equation of
state, increased symmetry energy and a lower value for the incompressibility
modulus which agrees quite well with the values used in the hydrodynamical
model for the supernovae explosion.
