  We conjecture the existence of a relationship between frustration and the
transition point at zero temperature of Ising spin glasses. The relation
reveals that, in several Ising spin glass models, the concentration of
ferromagnetic bonds is close to the critical concentration at zero temperature
when the output of a function about frustration is equal to unity. The function
is the derivative of the average number of frustrated plaquettes with respect
to the average number of antiferromagnetic bonds. This relation is conjectured
in Ising spin glasses with binary couplings on two-dimensional lattices,
hierarchical lattices, and three-body Ising spin glasses with binary couplings
on two-dimensional lattices. In addition, the same argument in the
Sherrington-Kirkpatrick model yields a point that is identical to the
replica-symmetric solution of the transition point at zero temperature.
