On the exact ground states of three-dimensional Ising spin glasses

Presents a new method based on linear programming to obtain the exact ground states of three-dimensional Ising spin glasses. Numerical simulations were carried out with the +or-J model and the Gaussian model with mean mu and variance sigma 2. Ferromagnetism disappears in the +or-J model at concentrations of negative bonds near 27%. This occurs, in the Gaussian model, when mu is near 0.6 sigma .