as h=2, when updating w_1^2, we have: G_{0:2}^λ =(1-λ)G_{0:1} + λG_{0:2} where G_{0:1}=R_1+\gamma\hat{v}(S_1,w_1^1) and G_{0:2}=R_1+\gamma{R_2}+\gamma\hat{v}(S_2,w_1^1), and then update G_{1:2}^λ =R_2 + \gamma\hat{v}(S_2,w_1^2).