cartpole
967990de5b3eac7b87d49a13c6834978-AuthorFeedback.pdf
Thank reviewers for the comments. Please find our responses below, with reference indices consistent with the paper . Q3-5: Meaning of the learned divergence? We agree that BC minimizes the policy KL divergence as what we noted in Sec. 4 (line 200). It is consistent with the literature, e.g., Sec. 2 in [Y u et al. arXiv:1909.09314].
Quantifying Memory Use in Reinforcement Learning with Temporal Range
Lafuente-Mercado, Rodney, Rus, Daniela, Rusch, T. Konstantin
How much does a trained RL policy actually use its past observations? We propose \emph{Temporal Range}, a model-agnostic metric that treats first-order sensitivities of multiple vector outputs across a temporal window to the input sequence as a temporal influence profile and summarizes it by the magnitude-weighted average lag. Temporal Range is computed via reverse-mode automatic differentiation from the Jacobian blocks $\partial y_s/\partial x_t\in\mathbb{R}^{c\times d}$ averaged over final timesteps $s\in\{t+1,\dots,T\}$ and is well-characterized in the linear setting by a small set of natural axioms. Across diagnostic and control tasks (POPGym; flicker/occlusion; Copy-$k$) and architectures (MLPs, RNNs, SSMs), Temporal Range (i) remains small in fully observed control, (ii) scales with the task's ground-truth lag in Copy-$k$, and (iii) aligns with the minimum history window required for near-optimal return as confirmed by window ablations. We also report Temporal Range for a compact Long Expressive Memory (LEM) policy trained on the task, using it as a proxy readout of task-level memory. Our axiomatic treatment draws on recent work on range measures, specialized here to temporal lag and extended to vector-valued outputs in the RL setting. Temporal Range thus offers a practical per-sequence readout of memory dependence for comparing agents and environments and for selecting the shortest sufficient context.