= Two-sublattice Ising mean-field approximation
{title2=$M_B=\tanh\beta(h+g-qJM_W)$}
On a regular <bipartite graph> with coordination number $q$, replace each bond product by $\sigma_B\sigma_W\simeq M_W\sigma_B+M_B\sigma_W-M_BM_W$. For $N$ sites there are $Nq/2$ bonds, so the constant in the effective <Hamiltonian> is $-NqJM_BM_W/2$. The <mean-field self-consistency equations> are $M_B=\tanh\beta(h+g-qJM_W)$ and $M_W=\tanh\beta(h-g-qJM_B)$. At zero fields the antisymmetric branch has a continuous <mean-field Ising critical bifurcation> at $k_BT_c=qJ$.
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