Off-Policy Deep Reinforcement Learning without Exploration

Scott FujimotoDavid MegerDoina Precup

article2018ICML2,164 citations

Introduces batch-constrained reinforcement learning to resolve extrapolation error, providing the first continuous control method capable of training effective deep reinforcement learning policies purely from fixed, offline datasets.

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Deploying reinforcement learning in real-world settings often requires training agents entirely on static, pre-collected datasets because active real-time exploration can be dangerous, costly, or operationally impractical. The article demonstrates why conventional off-policy reinforcement learning methods fail when restricted to fixed historical data and evaluates a new method designed to learn reliably under these constraints.

The authors analyze the core mathematical and empirical reasons standard algorithms break down when unable to interact with their environments. To resolve these failures, the article introduces Batch-Constrained deep Q-learning, a framework that constrains the agent's actions to stay close to the historical dataset while seeking the highest expected reward. The method uses a generative model to propose familiar actions, applies small optimized adjustments, and penalizes unfamiliar future states through a dual-network evaluation scheme. This approach was tested against established continuous control algorithms across standard simulated robotic benchmarks and diverse data collection regimes, including expert, concurrent, and noisy demonstrations.

The article establishes several key findings:

  1. Standard off-policy algorithms experience catastrophic failure and value estimation divergence in fixed-data settings because of extrapolation error, which causes agents to overestimate the performance of unfamiliar actions they cannot correct through real-time feedback.
  2. In high-dimensional benchmarks, the proposed batch-constrained method was the only tested algorithm that consistently matched or exceeded the performance of the data-generating policies across all evaluated tasks.
  3. The algorithm exhibited stable, non-divergent value estimates across all tests, remaining resilient even when trained on datasets containing substantial noise and suboptimal actions where traditional imitation learning failed.
  4. Mathematical analysis confirms that restricting policy actions to the historical data distribution is strictly necessary to prevent value estimation bias in fixed-data environments.

These findings have major practical implications for organizations seeking to train autonomous decision-making systems from historical logs without online trial-and-error. Conventional methods introduce severe operational risk by pursuing unrealistic outcomes based on flawed extrapolation. The batch-constrained paradigm provides a safer, more predictable approach by ensuring algorithms optimize strictly within operational regions where historical evidence exists, bridging the gap between conservative imitation and unconstrained optimization.

Organizations considering offline reinforcement learning should avoid deploying standard off-policy algorithms on fixed datasets and instead implement batch-constrained mechanisms that model the data collection distribution. Future work should evaluate this approach on larger-scale, real-world operational datasets and explore improved generative architectures, as sensitivity to hyperparameters in complex environments can still introduce value instability if the underlying generative model fails to capture the true data distribution.

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Abstract

Many practical applications of reinforcement learning constrain agents to learn from a fixed batch of data which has already been gathered, without offering further possibility for data collection. In this paper, we demonstrate that due to errors introduced by extrapolation, standard off-policy deep reinforcement learning algorithms, such as DQN and DDPG, are incapable of learning with data uncorrelated to the distribution under the current policy, making them ineffective for this fixed batch setting. We introduce a novel class of off-policy algorithms, batch-constrained reinforcement learning, which restricts the action space in order to force the agent towards behaving close to on-policy with respect to a subset of the given data. We present the first continuous control deep reinforcement learning algorithm which can learn effectively from arbitrary, fixed batch data, and empirically demonstrate the quality of its behavior in several tasks.

Table of Contents

  • 1 Introduction
  • 2 Background
  • 3 Extrapolation Error
  • 3.1 Extrapolation Error in Deep Reinforcement Learning
  • 4 Batch-Constrained Reinforcement Learning
  • 4.1 Addressing Extrapolation Error in Finite MDPs
  • 4.2 Batch-Constrained Deep Reinforcement Learning
  • 5 Experiments
  • 6 Related Work
  • 7 Conclusion
  • References
  • A Missing Proofs
  • A.1 Proofs and Details from Section 4.1
  • A.2 Sketch of the Proof of Convergence of Q-Learning
  • B Missing Graphs
  • B.1 Extrapolation Error in Deep Reinforcement Learning
  • B.2 Complete Experimental Results
  • C Extrapolation Error in Kernel-Based Reinforcement Learning
  • D Additional Experiments
  • D.1 Ablation Study of Perturbation Model
  • D.2 Uncertainty Estimation for Batch-Constrained Reinforcement Learning
  • D.3 Random Behavioral Policy Study
  • E Missing Background
  • E.1 Variational Auto-Encoder
  • F Experimental Details
  • G Implementation Details

Knowls

  1. Knowl 1 — Batch-Constrained Deep Q-Learning Policy Formulation via Generative and Perturbation Networks

    model/method

    Batch-Constrained deep Q-learning (BCQ) enforces a batch constraint in high-dimensional continuous action spaces by combining a state-conditioned generative model with an action perturbation model and deep Q-networks.

    To restrict action selection to state-action pairs (s,a)(s, a) with high density under the fixed batch B\mathcal{B}, BCQ models the conditional action distribution PB(as)P_B(a|s) using a conditional Variational Auto-Encoder (VAE) Gω(s)={Eω1(s,a),Dω2(s,z)}G_\omega(s) = \{E_{\omega_1}(s, a), D_{\omega_2}(s, z)\}. The encoder Eω1E_{\omega_1} maps (s,a)(s, a) to Gaussian latent parameters μ,σ\mu, \sigma, and the decoder Dω2D_{\omega_2} reconstructs the action from (s,z)(s, z), where z=μ+σϵz = \mu + \sigma \odot \epsilon with ϵN(0,I)\epsilon \sim \mathcal{N}(0, I). The VAE is trained by minimizing the loss:

    LVAE=(s,a)BDω2(s,z)a2+12JDKL(N(μ,σ)N(0,I))\mathcal{L}_{\text{VAE}} = \sum_{(s,a) \in \mathcal{B}} \|D_{\omega_2}(s, z) - a\|^2 + \frac{1}{2J} D_{\text{KL}}(\mathcal{N}(\mu, \sigma) \parallel \mathcal{N}(0, I))

    where J=2dim(A)J = 2 \dim(\mathcal{A}) is the latent vector dimensionality, and the Gaussian KL divergence expands as:

    DKL(N(μ,σ)N(0,I))=12j=1J(1+log(σj2)μj2σj2)D_{\text{KL}}(\mathcal{N}(\mu, \sigma) \parallel \mathcal{N}(0, I)) = -\frac{1}{2} \sum_{j=1}^J \left( 1 + \log(\sigma_j^2) - \mu_j^2 - \sigma_j^2 \right)

    During inference, latent vectors zz are clipped to [0.5,0.5][-0.5, 0.5] to avoid sampling out-of-distribution actions.

    To increase action diversity while remaining close to the batch distribution, a perturbation model ξϕ(s,a,Φ)\xi_\phi(s, a, \Phi) outputs an additive adjustment bounded in [Φ,Φ][-\Phi, \Phi] via a tanh\tanh activation scaled by Φ\Phi. The perturbation network is trained with the deterministic policy gradient on actions sampled from Gω(s)G_\omega(s) using critic Qθ1Q_{\theta_1}:

    ϕargmaxϕ(s,a)BQθ1(s,a+ξϕ(s,a,Φ)),aGω(s)\phi \leftarrow \arg\max_\phi \sum_{(s,a) \in \mathcal{B}} Q_{\theta_1}(s, a + \xi_\phi(s, a, \Phi)), \quad a \sim G_\omega(s)

    The resulting policy π(s)\pi(s) samples nn candidate actions from Gω(s)G_\omega(s), perturbs each, and greedily selects the action that maximizes Qθ1Q_{\theta_1}:

    π(s)=argmaxai+ξϕ(s,ai,Φ)Qθ1(s,ai+ξϕ(s,ai,Φ)),{aiGω(s)}i=1n\pi(s) = \arg\max_{a_i + \xi_\phi(s, a_i, \Phi)} Q_{\theta_1}(s, a_i + \xi_\phi(s, a_i, \Phi)), \quad \{a_i \sim G_\omega(s)\}_{i=1}^n

  2. Knowl 2 — Batch-Constrained Deep Q-Learning (BCQ) Full Algorithm

    algorithm

    Batch-Constrained deep Q-learning (BCQ) trains an off-policy actor-critic agent on a fixed batch dataset B\mathcal{B} without online exploration by coupling a generative conditional VAE, a bounded action perturbation network, and twin Q-networks.

    Algorithm: Batch-Constrained deep Q-learning (BCQ)
    Input: Batch dataset B\mathcal{B}, horizon TT, target update rate τ=0.005\tau = 0.005, mini-batch size N=100N = 100, maximum perturbation Φ=0.05\Phi = 0.05, candidate sample count n=10n = 10, minimum weighting λ=0.75\lambda = 0.75
    Output: Policy networks Gω,ξϕG_\omega, \xi_\phi and Q-networks Qθ1,Qθ2Q_{\theta_1}, Q_{\theta_2}
    Initialize Q-networks Qθ1,Qθ2Q_{\theta_1}, Q_{\theta_2}, perturbation network ξϕ\xi_\phi, and VAE Gω={Eω1,Dω2}G_\omega = \{E_{\omega_1}, D_{\omega_2}\} with random parameters θ1,θ2,ϕ,ω\theta_1, \theta_2, \phi, \omega
    Initialize target networks: θ1θ1\theta'_1 \leftarrow \theta_1, θ2θ2\theta'_2 \leftarrow \theta_2, ϕϕ\phi' \leftarrow \phi
    for t=1t = 1 to TT do
        Sample mini-batch of NN transitions (s,a,r,s)(s, a, r, s') from B\mathcal{B}
        μ,σ=Eω1(s,a)\mu, \sigma = E_{\omega_1}(s, a)
        Sample zN(μ,σ)z \sim \mathcal{N}(\mu, \sigma)
        a~=Dω2(s,z)\tilde{a} = D_{\omega_2}(s, z)
        ωargminω(aa~)2+12JDKL(N(μ,σ)N(0,I))\omega \leftarrow \arg\min_\omega \sum (a - \tilde{a})^2 + \frac{1}{2J} D_{\text{KL}}(\mathcal{N}(\mu, \sigma) \parallel \mathcal{N}(0, I))
        Sample nn actions per next state: {aiGω(s)}i=1n\{a_i \sim G_\omega(s')\}_{i=1}^n
        Perturb each next-state candidate: {aiai+ξϕ(s,ai,Φ)}i=1n\{a_i \leftarrow a_i + \xi_{\phi'}(s', a_i, \Phi)\}_{i=1}^n
        Compute target value: y=r+γmaxai[λminj=1,2Qθj(s,ai)+(1λ)maxj=1,2Qθj(s,ai)]y = r + \gamma \max_{a_i} [ \lambda \min_{j=1,2} Q_{\theta'_j}(s', a_i) + (1-\lambda) \max_{j=1,2} Q_{\theta'_j}(s', a_i) ]
        Update critics: θjargminθj(yQθj(s,a))2\theta_j \leftarrow \arg\min_{\theta_j} \sum (y - Q_{\theta_j}(s, a))^2 for j{1,2}j \in \{1, 2\}
        Sample current-state actions: aGω(s)a \sim G_\omega(s)
        Update perturbation network: ϕargmaxϕQθ1(s,a+ξϕ(s,a,Φ))\phi \leftarrow \arg\max_\phi \sum Q_{\theta_1}(s, a + \xi_\phi(s, a, \Phi))
        Update target networks: θjτθj+(1τ)θj\theta'_j \leftarrow \tau \theta_j + (1 - \tau)\theta'_j for j{1,2}j \in \{1, 2\}, and ϕτϕ+(1τ)ϕ\phi' \leftarrow \tau \phi + (1 - \tau)\phi'
    end for

    All networks are trained with the Adam optimizer at a learning rate of 10310^{-3} and discount factor γ=0.99\gamma = 0.99. Critic and perturbation networks have 2 hidden layers with 400 and 300 ReLU units; the VAE encoder and decoder use 2 hidden layers with 750 ReLU units.

  3. Knowl 3 — Uncertainty-Penalized Learning Target in BCQ

    equation

    To penalize unfamiliar states and prevent value overestimation during off-policy updates on a fixed dataset B\mathcal{B}, BCQ trains twin Q-networks Qθ1Q_{\theta_1} and Qθ2Q_{\theta_2} using a convex combination of the minimum and maximum target critic evaluations:

    y=r+γmaxai[λminj=1,2Qθj(s,ai)+(1λ)maxj=1,2Qθj(s,ai)]y = r + \gamma \max_{a_i} \left[ \lambda \min_{j=1,2} Q_{\theta'_j}(s', a_i) + (1 - \lambda) \max_{j=1,2} Q_{\theta'_j}(s', a_i) \right]

    where λ[0.5,1.0]\lambda \in [0.5, 1.0] is a fixed weighting hyperparameter (set to λ=0.75\lambda = 0.75), and candidate actions are given by:

    ai=a~i+ξϕ(s,a~i,Φ),a~iGω(s),i=1,,na_i = \tilde{a}_i + \xi_{\phi'}(s', \tilde{a}_i, \Phi), \quad \tilde{a}_i \sim G_\omega(s'), \quad i = 1, \dots, n

    Both Q-networks minimize the squared Bellman error against the shared target yy:

    Lvalue,j=1Bmini(s,a,r,s)Bmini(yQθj(s,a))2,j{1,2}\mathcal{L}_{\text{value}, j} = \frac{1}{|\mathcal{B}_{\text{mini}}|} \sum_{(s,a,r,s') \in \mathcal{B}_{\text{mini}}} \left( y - Q_{\theta_j}(s, a) \right)^2, \quad j \in \{1, 2\}

    Setting λ>0.5\lambda > 0.5 penalizes high variance across critic estimates in regions of state uncertainty, directing the policy toward actions that lead to familiar transitions present in the batch.

  4. Knowl 4 — Extrapolation Error and Tabular Error Decomposition in Batch Reinforcement Learning

    theoretical result

    In a Markov decision process M=(S,A,pM,r,γ)M = (\mathcal{S}, \mathcal{A}, p_M, r, \gamma), learning a Q-function exclusively from a fixed batch of transitions B\mathcal{B} introduces extrapolation error, defined as the discrepancy between the true value function Qπ(s,a)Q^\pi(s, a) in MM and the value function QBπ(s,a)Q_B^\pi(s, a) learned in the empirical batch MDP MBM_B.

    The batch MDP MBM_B shares the state and action spaces of MM with an additional terminal state sinits_{\text{init}}, having empirical transition probabilities:

    pB(ss,a)=N(s,a,s)s~N(s,a,s~)p_B(s'|s, a) = \frac{N(s, a, s')}{\sum_{\tilde{s}} N(s, a, \tilde{s})}

    if s~N(s,a,s~)>0\sum_{\tilde{s}} N(s, a, \tilde{s}) > 0, and pB(sinits,a)=1p_B(s_{\text{init}}|s, a) = 1 otherwise with r(s,a,sinit)=Q0(s,a)r(s, a, s_{\text{init}}) = Q_0(s, a). Performing standard tabular Q-learning by sampling uniformly from B\mathcal{B} converges to the optimal value function under MBM_B.

    The tabular extrapolation error ϵMDP(s,a)=Qπ(s,a)QBπ(s,a)\epsilon_{\text{MDP}}(s, a) = Q^\pi(s, a) - Q_B^\pi(s, a) satisfies the Bellman-like recurrence:

    ϵMDP(s,a)=s(pM(ss,a)pB(ss,a))(r(s,a,s)+γaπ(as)QBπ(s,a))+spM(ss,a)γaπ(as)ϵMDP(s,a)\epsilon_{\text{MDP}}(s, a) = \sum_{s'} (p_M(s'|s, a) - p_B(s'|s, a)) \left( r(s, a, s') + \gamma \sum_{a'} \pi(a'|s') Q_B^\pi(s', a') \right) + \sum_{s'} p_M(s'|s, a) \gamma \sum_{a'} \pi(a'|s') \epsilon_{\text{MDP}}(s', a')

    The total weighted extrapolation error under policy state-visitation μπ(s)\mu^\pi(s) is given by:

    ϵMDPπ=sμπ(s)aπ(as)ϵMDP(s,a)\epsilon_{\text{MDP}}^\pi = \sum_s \mu^\pi(s) \sum_a \pi(a|s) |\epsilon_{\text{MDP}}(s, a)|

    For any reward function, ϵMDPπ=0\epsilon_{\text{MDP}}^\pi = 0 if and only if pB(ss,a)=pM(ss,a)p_B(s'|s, a) = p_M(s'|s, a) for all sSs' \in \mathcal{S} and all (s,a)(s, a) satisfying μπ(s)>0\mu^\pi(s) > 0 and π(as)>0\pi(a|s) > 0.

  5. Knowl 5 — Zero Extrapolation Error for Batch-Constrained Policies in Deterministic MDPs

    theoretical result

    Let a batch B\mathcal{B} be coherent, defined as satisfying sBs' \in \mathcal{B} for all (s,a,s)B(s, a, s') \in \mathcal{B} unless ss' is a terminal state. Let a policy π\pi be batch-constrained (denoted πΠB\pi \in \Pi_B) if (s,a)B(s, a) \in \mathcal{B} for every (s,a)(s, a) with μπ(s)>0\mu^\pi(s) > 0 and π(as)>0\pi(a|s) > 0.

    In a deterministic MDP, for all reward functions, the total extrapolation error ϵMDPπ=0\epsilon_{\text{MDP}}^\pi = 0 if and only if the policy π\pi is batch-constrained. Furthermore, if B\mathcal{B} is coherent, at least one batch-constrained policy exists provided the initial state s0Bs_0 \in \mathcal{B}.

  6. Knowl 6 — Batch-Constrained Q-Learning (BCQL) and Convergence Guarantees

    algorithm

    Batch-Constrained Q-learning (BCQL) is a tabular reinforcement learning algorithm that restricts action updates to state-action pairs present in a batch B\mathcal{B}.

    Given a sampled transition (s,a,r,s)B(s, a, r, s') \in \mathcal{B}, BCQL applies the temporal difference update:

    Q(s,a)(1α)Q(s,a)+α(r+γmaxa s.t. (s,a)BQ(s,a))Q(s, a) \leftarrow (1 - \alpha) Q(s, a) + \alpha \left( r + \gamma \max_{a' \text{ s.t. } (s', a') \in \mathcal{B}} Q(s', a') \right)

    BCQL possesses the following convergence guarantees:

    1. Under Robbins-Monro conditions on learning rate α\alpha (tαt=,tαt2<\sum_t \alpha_t = \infty, \sum_t \alpha_t^2 < \infty) and infinite state-action visitation across the true MDP, BCQL converges to the optimal value function QQ^*.
    2. In a deterministic MDP with a coherent batch B\mathcal{B}, under Robbins-Monro conditions and uniform sampling from B\mathcal{B}, BCQL converges to QBπ(s,a)Q_B^{\pi^*}(s, a), where π(s)=argmaxa s.t. (s,a)BQBπ(s,a)\pi^*(s) = \arg\max_{a \text{ s.t. } (s, a) \in \mathcal{B}} Q_B^{\pi^*}(s, a) is the optimal batch-constrained policy.
    3. The converged policy π\pi^* satisfies Qπ(s,a)Qπ(s,a)Q^{\pi^*}(s, a) \ge Q^\pi(s, a) for all batch-constrained policies πΠB\pi \in \Pi_B and all (s,a)B(s, a) \in \mathcal{B}, guaranteeing that BCQL matches or outperforms the data-generating behavioral policy from any starting state in B\mathcal{B}.
  7. Knowl 7 — Extrapolation Error and Value Divergence in Standard Off-Policy Deep Actor-Critic Algorithms

    empirical result

    When standard deep actor-critic algorithms (such as DDPG and discretized DQN) are trained purely off-policy on fixed batch datasets without environment interaction, extrapolation error causes severe value function divergence and poor policy performance:

    1. Final Buffer (1 million transitions collected by a DDPG agent trained with N(0,0.5)\mathcal{N}(0, 0.5) exploration noise on Hopper-v1): Off-policy DDPG fails to match the average return of the batch trajectories, producing highly erratic critic estimates (fluctuating between 4×104-4 \times 10^4 and +6×104+6 \times 10^4).
    2. Concurrent Learning (1 million transitions shared between an active behavioral DDPG agent with N(0,0.1)\mathcal{N}(0, 0.1) noise and an offline DDPG agent): The offline agent achieves significantly lower returns (rarely exceeding 1000) than the behavioral agent (which reaches returns 2500\sim 2500), with value estimates diverging over 15001500, demonstrating that differences in initial policy state distributions are sufficient to trigger detrimental extrapolation error.
    3. Imitation (1 million expert transitions collected by trained DDPG on Hopper-v1): The offline DDPG agent quickly selects out-of-distribution non-expert actions due to overestimation bias, driving Q-value estimates to diverge beyond 7×1077 \times 10^7 and collapsing policy return to near zero.
  8. Knowl 8 — Comparative Performance and Value Stability of BCQ Across Continuous Control Tasks

    empirical result

    BCQ was evaluated across OpenAI Gym continuous control tasks (HalfCheetah-v1, Hopper-v1, Walker2d-v1) under four fixed batch regimes against DDPG, independently discretized DQN, feedforward Behavioral Cloning (BC), and a VAE-based Behavioral Cloning baseline (VAE-BC):

    1. Final Buffer (1M exploration transitions): BCQ matches or exceeds the behavioral policy return (e.g., reaching 8000\sim 8000 in HalfCheetah-v1, 1500\sim 1500 in Hopper-v1, and 2000\sim 2000 in Walker2d-v1), whereas DDPG and DQN fail.
    2. Concurrent Learning (1M transitions): BCQ outperforms or matches the active behavioral agent across all environments and maintains stable Q-estimates matching Monte Carlo true returns.
    3. Expert Imitation (1M expert transitions): BCQ maintains high return (matching BC and VAE-BC at 10000\sim 10000 on HalfCheetah-v1, 3500\sim 3500 on Hopper-v1, and 3500\sim 3500 on Walker2d-v1) with completely stable value estimates, whereas DDPG and DQN diverge.
    4. Imperfect Demonstrations (100k transitions with 30% uniform random action selection and N(0,0.3)\mathcal{N}(0, 0.3) Gaussian noise): Standard BC and VAE-BC achieve poor returns (e.g., <2000<2000 in HalfCheetah-v1), while BCQ rapidly attains high expert-level returns (>6000>6000 in HalfCheetah-v1, >2500>2500 in Hopper-v1, >2000>2000 in Walker2d-v1) in under 10510^5 iterations, successfully filtering noisy transitions.
  9. Knowl 9 — Generative Action Constraints Versus Ensemble Uncertainty Minimization in Batch RL

    empirical result

    To evaluate whether uncertainty estimation alone can prevent extrapolation error in batch reinforcement learning, an actor-critic baseline was tested on the Hopper-v1 expert imitation task where the policy πϕ\pi_\phi is trained to minimize the standard deviation across ensembles of Q-networks of size N{4,10}N \in \{4, 10\}:

    ϕargminϕ(s,a)Bσ({Qθi(s,a)}i=1N)\phi \leftarrow \arg\min_\phi \sum_{(s,a) \in \mathcal{B}} \sigma\left( \left\{ Q_{\theta_i}(s, a) \right\}_{i=1}^N \right)

    While ensemble variance minimization stabilizes the critic estimates (keeping values under 400), it fails to restrict the actor's actions to the expert distribution, yielding inferior policy returns (plateauing around 1000 to 1500 return) compared to BCQ (which achieves 3000\sim 3000 return). Constraining the candidate action space via a conditional generative model provides an effective batch constraint without requiring computationally expensive large ensembles or delicate weighting between value maximization and uncertainty penalties.

  10. Knowl 10 — Extrapolation Error in Kernel-Based Batch Reinforcement Learning

    theoretical result

    Extrapolation error affects non-parametric batch reinforcement learning methods such as Kernel-Based Reinforcement Learning (KBRL). Given a batch B\mathcal{B}, density kernel kτ(s,sBa)=ϕ(ssBa/τ)k_\tau(s, s_B^a) = \phi(\|s - s_B^a\| / \tau), and normalized weights κτa(s,sBa)\kappa_\tau^a(s, s_B^a), KBRL computes state-action values as:

    Q(s,a)=(sBa,a,r,sBa)Bκτa(s,sBa)[r+γV(sBa)],V(s)=maxa s.t. (s,a)BQ(s,a)Q(s, a) = \sum_{(s_B^a, a, r, s_B'^a) \in \mathcal{B}} \kappa_\tau^a(s, s_B^a) \left[ r + \gamma V(s_B'^a) \right], \quad V(s') = \max_{a \text{ s.t. } (s', a) \in \mathcal{B}} Q(s', a)

    Consider a deterministic two-state MDP with states {s0,s1}\{s_0, s_1\}, actions {a0,a1}\{a_0, a_1\}, and transitions/rewards: pM(s1s0,a1)=1p_M(s_1|s_0, a_1) = 1 with r=1r=1; pM(s0s1,a0)=1p_M(s_0|s_1, a_0) = 1 with r=0r=0; and self-loops on a0a_0 at s0s_0 and a1a_1 at s1s_1 with r=0r=0. When provided with optimal batch B={(s0,a1,1,s1),(s1,a0,0,s0)}\mathcal{B} = \{(s_0, a_1, 1, s_1), (s_1, a_0, 0, s_0)\}, KBRL estimates:

    Q(,a1)=11γ2,Q(,a0)=γ1γ2Q(\cdot, a_1) = \frac{1}{1 - \gamma^2}, \quad Q(\cdot, a_0) = \frac{\gamma}{1 - \gamma^2}

    Because the kernel assigns the same value across all states for each observed action, KBRL estimates Q(s1,a1)=11γ2>Q(s1,a0)=γ1γ2Q(s_1, a_1) = \frac{1}{1 - \gamma^2} > Q(s_1, a_0) = \frac{\gamma}{1 - \gamma^2}, leading argmaxaQ(s,a)\arg\max_a Q(s, a) to select a1a_1 at s1s_1 (an unseen transition yielding reward 0 and self-loop), resulting in a degenerate policy that fails to learn the optimal behavior.

Coverage note — None was omitted; all major theoretical results (Theorems 1-4, Lemma 1, KBRL analysis), algorithmic components (BCQL, BCQ VAE and perturbation architecture, uncertainty target), and empirical evaluations (Hopper, HalfCheetah, Walker2d benchmarks, ensemble comparisons, toy random policy experiments) are fully covered.

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Citation

MLA
Fujimoto, S., et al. “Off-Policy Deep Reinforcement Learning Without Exploration”. arXiv, 2018, http://arxiv.org/abs/1812.02900v3.
APA
Fujimoto, S., Meger, D., & Precup, D. (2018). Off-Policy Deep Reinforcement Learning without Exploration. arXiv. http://arxiv.org/abs/1812.02900v3
Chicago
Fujimoto, S., D. Meger, and D. Precup. 2018. “Off-Policy Deep Reinforcement Learning Without Exploration”. arXiv. http://arxiv.org/abs/1812.02900v3.
Harvard
Fujimoto, S., Meger, D. and Precup, D. (2018) “Off-Policy Deep Reinforcement Learning without Exploration”, arXiv [Preprint]. Available at: http://arxiv.org/abs/1812.02900v3.
Vancouver
1. Fujimoto S, Meger D, Precup D (2018) Off-Policy Deep Reinforcement Learning without Exploration. arXiv

BibTeX

@article{fujimoto2018off,
  title = {Off-Policy Deep Reinforcement Learning without Exploration},
  author = {Fujimoto, Scott and Meger, David and Precup, Doina},
  year = {2018},
  journal = {arXiv},
  url = {http://arxiv.org/abs/1812.02900v3},
  eprint = {1812.02900}
}
Metadata:arXiv

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