lazy evaluation actions
In the policy improvement step, the next policy is obtained by computing a greedy policy with respect to 



Q


{\displaystyle Q}

: Given a state 



s


{\displaystyle s}

, this new policy returns an action that maximizes 



Q
(
s
,
⋅
)


{\displaystyle Q(s,\cdot )}

. In practice lazy evaluation can defer the computation of the maximizing actions to when they are needed.
