Let l and m be natural numbers with l≥2 and m≥1, let A be a nonempty subset of Euclidean space Rm, let β be a transition-rate family on l states with control set A and rate bound B, and let (U,V,βˉ) be a twice continuously differentiable extension of β with derivative bound K, points of U×V being written x=(Σ,α) as in that definition.
The extended aggregate state drift of (U,V,βˉ) is the function bˉ:U×V→Rl whose components are
bˉγ(Σ,α)=σ:σ=γ∑(Σσβˉ(σ,γ,Σ,α)−Σγβˉ(γ,σ,Σ,α))(γ∈{1,…,l}),
where the sum runs over σ∈{1,…,l} with σ=γ.