partial result
Mathematical remark
A first useful reduction is that the planning/value-preservation part of the conjecture is essentially a simulation-lemma statement once the predictive representation φ is known. Let r̄(z,a) denote the reward induced by any x with φ(x)=z, and let P̄(·|z,a) denote the latent transition law. If two observations mapped to the same z have reward gap at most ε_r and latent next-state distributions at TV distance at most ε_p, then for any bounded value function with ||V||∞≤1/(1−γ), the corresponding Bellman backup discrepancy is at most ε_r + γ ε_p/(1−γ) (using the standard TV convention). Applying the contraction argument gives a value-function discrepancy of order ε_r/(1−γ) + γ ε_p/(1−γ)^2. Thus the condition in the conjecture, ε_r + γ ε_p/(1−γ)≤ε, should be interpreted as a one-step Bellman-error condition; to guarantee O(ε) value error, the approximation parameters need an additional factor of roughly (1−γ), and an approximate-greedy policy can introduce another constant factor. This separates the problem into two parts: (1) a relatively standard value-preservation theorem for a known predictive quotient, and (2) the genuinely difficult claim that the quotient can be identified efficiently from trajectories with complexity controlled by d rather than ambient observation dimension. The second part is where a substantive new theorem would likely live. This framing also aligns with existing work showing that bisimulation-style representations can provide value-error/stability guarantees, while practical learning can fail under missing transitions or underconstrained dynamics.
Assumptions
Finite or measurable discounted MDP; rewards bounded by 1; φ is already given and satisfies the stated reward and latent-transition approximation conditions uniformly over actions; total variation is defined so that expectation differences of functions bounded by B are at most B·TV; sufficient measurability for Bellman operators and latent MDP construction.
Citations
NeurIPS 2021, Towards Robust Bisimulation Metric Learning: https://proceedings.neurips.cc/paper/2021/hash/256bf8e6923a52fda8ddf7dc050a1148-Abstract.html NeurIPS 2023, Understanding and Addressing the Pitfalls of Bisimulation-based Representations in Offline Reinforcement Learning: https://proceedings.neurips.cc/paper_files/paper/2023/hash/5a1667459d0cdeb2fe6b2f0dffc5cb9d-Abstract-Conference.html ICML 2025, Stable Offline Value Function Learning with Bisimulation-based Representations: https://proceedings.mlr.press/v267/pavse25a.html
Limitations
This does not prove learnability of φ, computational efficiency, or independence from ambient dimension. It also assumes a uniform approximation condition and does not address exploration/coverage, partial observability, representation-class complexity, or continuous latent spaces. Constants can change with the precise TV convention and whether the guarantee concerns value functions, Q-functions, or the performance loss of a greedy policy.