  A new combinatorial, analytical approach to the ground-state energy problem
of spin glasses with different concentrations of +/- J interactions is
developed. The energy e_0 is expressed in terms of the fraction of broken bonds
mu_0 and expanded into a fast converging series of the average length of a
segment between two frustrated plaquettes of a minimum-weighted perfect
matching Lambda_mean. The concept of so called diagram stability s is
introduced in order to calculate coefficients of this expansion. Finally, the
fraction mu_0 as a function of the concentration p of negative bonds is
obtained for triangular and square infinite lattices in excellent accordance
with numerical simulations of large adequate systems.
