Machine Learning.
function: Describes how value is to take a particular action in a particular state. qπ(s,a)=Eπ[Gt |St =s,At =a] Both State-value function and action-value function can be decomposed into immediate reward plus discounted value of successor state. vπ(s) = Eπ [Rt+1 + γvπ(St+1) | St = s]