Efficient Single-Loop Deep Actor-Critic Algorithm for Constrained Reinforcement Learning with Provable Convergence
Keskeiset käsitteet
The proposed single-loop deep actor-critic (SLDAC) algorithm can efficiently solve constrained reinforcement learning problems with non-convex stochastic constraints and high interaction cost, while provably converging to a Karush-Kuhn-Tucker (KKT) point.
Tiivistelmä
The paper proposes a single-loop deep actor-critic (SLDAC) algorithm for solving constrained reinforcement learning (CRL) problems. The key features of the SLDAC algorithm are:
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Actor Module:
- Adopts the constrained stochastic successive convex approximation (CSSCA) method to handle the non-convex stochastic objective and constraints.
- Constructs surrogate functions to approximate the original objective and constraint functions, and solves a sequence of convex optimization problems.
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Critic Module:
- Uses temporal-difference (TD) learning to update the critic deep neural networks (DNNs).
- Performs the critic update only once or a few finite times per iteration, simplifying the algorithm to a single-loop framework.
- Allows reusing observations from the old policy to reduce the agent-environment interaction cost.
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Theoretical Analysis:
- Proves that the proposed SLDAC can converge to a Karush-Kuhn-Tucker (KKT) point of the original problem almost surely, despite the biased policy gradient estimation induced by the single-loop design and observation reuse.
- Provides theoretical results on the asymptotic consistency of the estimated function values and policy gradients, as well as the finite-time convergence rates of the critic DNNs.
The SLDAC algorithm can achieve superior performance with much lower interaction cost compared to existing deep actor-critic algorithms for constrained reinforcement learning.
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arxiv.org
A Single-Loop Deep Actor-Critic Algorithm for Constrained Reinforcement Learning with Provable Convergence
Tilastot
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Lainaukset
"The single-loop design and the observation reuse effectively reduce the agent-environment interaction cost and computational complexity."
"Despite the biased policy gradient estimation incurred by the single-loop design and observation reuse, we prove that the SLDAC with a feasible initial point can converge to a Karush-Kuhn-Tuker (KKT) point of the original problem almost surely."
Syvällisempiä Kysymyksiä
How can the SLDAC algorithm be extended to handle partial observability or multi-agent settings?
The SLDAC (Single-Loop Deep Actor-Critic) algorithm can be extended to handle partial observability by incorporating techniques from partially observable Markov decision processes (POMDPs). In a POMDP, the agent does not have access to the complete state of the environment, which can be addressed by using a belief state representation. This involves maintaining a probability distribution over possible states based on the history of observations and actions taken.
To implement this in the SLDAC framework, the actor module can be modified to parameterize the policy based on the belief state rather than the actual state. This can be achieved by integrating recurrent neural networks (RNNs) or long short-term memory (LSTM) networks into the actor's architecture, allowing it to process sequences of observations and maintain a hidden state that captures relevant information over time.
In multi-agent settings, the SLDAC algorithm can be adapted by treating each agent as an independent actor within a shared environment. The critic module can be designed to account for the actions of other agents, potentially using a centralized critic that observes the actions and states of all agents to provide more accurate value estimates. Additionally, communication protocols can be established among agents to share information about their observations and actions, enhancing coordination and improving overall performance.
What are the potential limitations of the CSSCA method used in the actor module, and how can they be addressed?
The Constrained Stochastic Successive Convex Approximation (CSSCA) method, while effective in handling non-convex stochastic objectives and constraints, has several potential limitations. One major limitation is its reliance on the convexity assumption for the surrogate functions. If the approximation of the objective or constraints is not sufficiently accurate, it may lead to suboptimal policy updates and hinder convergence.
To address this limitation, one approach is to incorporate adaptive learning rates that adjust based on the performance of the CSSCA method. By monitoring the convergence behavior and the accuracy of the approximations, the algorithm can dynamically modify the step sizes used in the updates, allowing for more robust learning in challenging environments.
Another limitation is the potential for high variance in the gradient estimates due to the stochastic nature of the updates. This can be mitigated by employing variance reduction techniques, such as using control variates or importance sampling, to improve the stability and reliability of the gradient estimates. Additionally, integrating experience replay mechanisms can help in reusing past experiences more effectively, thereby reducing the variance in the policy gradient estimates.
Can the SLDAC framework be applied to other types of constrained optimization problems beyond reinforcement learning?
Yes, the SLDAC framework can be applied to other types of constrained optimization problems beyond reinforcement learning. The underlying principles of the SLDAC algorithm, particularly the single-loop structure and the use of deep neural networks for function approximation, are applicable to a wide range of optimization scenarios.
For instance, in traditional optimization problems where the objective function and constraints are non-convex, the SLDAC framework can be adapted to optimize a surrogate function that approximates the original objective while satisfying the constraints. This can be particularly useful in fields such as operations research, finance, and engineering design, where complex, high-dimensional optimization problems are common.
Moreover, the CSSCA method can be utilized in various constrained optimization contexts, such as resource allocation, scheduling, and network design, where the goal is to maximize an objective function while adhering to specific constraints. By leveraging the SLDAC framework, practitioners can benefit from the algorithm's ability to handle non-convexities and stochastic elements, making it a versatile tool for tackling diverse optimization challenges.