the kl divergence term appears frequently in formulations of machine learning, often as a term in the loss function. in relation to language models it typically appears in the objective at the reinforcement learning stage rlfh maxπθEx∼D,y∼πθ(y∣x)[rϕ(x,y)]−βDKL[πθ(y∣x)∣∣πSFT(y∣x)]. grpo $$ J_{GRPO} (\theta) = \mathbb{E} \left[ \frac{1}{G} \sum_{i=1}^{G} \frac{1}{|o_i|} \sum_{t=1}^{|o_i|} \left( \min \left( r \hat{A}{i,t}, \text{clip} \left(r, 1 - \epsilon, 1 + \epsilon \right) \hat{A}{i,t} \right)...