Paradigmatic non-equilibrium model: particles hop right with rate p if next site empty
Three phases: LD (α<β,α<1/2): bulk density ρ=α; HD (β<α,β<1/2): ρ=1-β; MC (α,β>1/2): ρ=1/2, J=1/4. Shock front in coexistence. Domain wall theory.