arXiv:2511. 19849v2 Announce Type: replace-cross Abstract: Recurrence objectives, where a target region must be visited infinitely often, are a fundamental class of specifications for Markov decision processes (MDPs) and form the core of $\omega$-regular and linear temporal logic (LTL) objectives.
By Dominik Wagner, Leon Witzman, Luke Ong
The paper presents an exponential lower bound on the number of iterations required by Howard's policy iteration algorithm for deterministic discounted Markov decision processes with at most two actions per state, when the discount factor is part of the input. This result shows that Howard's method cannot be strongly polynomial in this setting and establishes an exponential gap compared to the simplex method with Dantzig's pivoting rule, which remains strongly polynomial. Even with rewards limited to logarithmic bit length, a stretched‑exponential lower bound is achieved, highlighting a fundamental difference between decentralized, simultaneous improvements and Dantzig's coordinated single‑action selection.
By Han Zhong, Yinyu Ye
We study infinite-horizon average-reward constrained Markov decision processes (CMDPs) under the weakly communicating assumption. Existing high-probability guarantees for this setting either require c...
arXiv:2603. 23461v2 Announce Type: replace Abstract: We study reinforcement learning (RL) with linear function approximation in Markov Decision Processes (MDPs) satisfying \emph{linear Bellman completeness} -- a fundamental setting where the Bellman backup of any linear value function remains linear.
By Zakaria Mhammedi, Alexander Rakhlin, Nneka Okolo
arXiv:2601. 23229v2 Announce Type: replace Abstract: Markov decision processes (MDPs) are a fundamental model in sequential decision making.
By Ali Asadi, Krishnendu Chatterjee, Ehsan Goharshady, Mehrdad Karrabi, Alipasha Montaseri, Carlo Pagano
The paper investigates adaptive policy portfolios for Robust Markov Decision Processes (RMDPs), proposing finite sets of memoryless randomized policies generated offline and selected online. It introduces robust regret as a metric for portfolio quality, comparing each portfolio member’s performance to the optimal policy for each plausible environment. The authors provide complexity-theoretic results showing that certifying and synthesizing such portfolios is highly intractable, and they present an offline construction method that can be specialized at runtime.