w(o)=Ao(u),(v)IIba() (u,w)∈E ∈V partition function: Z(G)=∑w(a) o∈{0,1}v Gibbs measure: Pr(a)= w(o) ZG) marginal probability: Pr(σ(v)=0|OA) 1/n additive error for FPTAS for Z(G) marginal in poly(n)-timew(￾) = ￾ (u,v)￾E A￾(u),￾(v) ￾ v￾V b￾(v) marginal probability: 1/n additive error for marginal in poly(n)-time FPTAS for Z(G) Gibbs measure: 8Z(￾) = w(￾) Z(G) = ￾ ￾￾{0,1}V partition function: Z(G) w(￾) 8Z(￾(v) = 0 | ￾￾)