Difference between revisions of "Deep Reinforcement Learning (DRL)"

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(MERLIN)
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== MERLIN ==
 
In deep learning, this is the driving thesis behind external, key-value-based memory stores. This idea is not new; [http://arxiv.org/pdf/1410.5401.pdf Neural Turing Machines], one of the first and favorite papers I ever read, augmented neural nets with a differentiable, external memory store accessible via vector-valued “read” and “write” heads to specific locations. We can easily imagine this being extended into RL, where at any given time-step, an agent is given both its environment observation and memories relevant to its current state. That’s exactly what the recent MERLIN architecture extends upon. MERLIN has 2 components: a memory-based predictor (MBP), and a policy network. The MBP is responsible for compressing observations into useful, low-dimensional “state variables” to store directly into a key-value memory matrix. It is also responsible for passing relevant memories to the policy, which uses those memories and the current state to output actions.... MERLIN is not the only [[Deep Reinforcement Learning (DRL)]] to use external memory stores — all the way back in 2016, researchers were already applying this idea in an MQN, or Memory Q-Network [http://towardsdatascience.com/advanced-reinforcement-learning-6d769f529eb3 Beyond DQN/A3C: A Survey in Advanced Reinforcement Learning | Joyce Xu - Towards Data Science]
 
 
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== Importance Weighted Actor-Learner Architecture (IMPALA) ==
 
== Importance Weighted Actor-Learner Architecture (IMPALA) ==

Revision as of 19:51, 1 September 2019

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OTHER: Policy Gradient Methods

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Goal-oriented algorithms, which learn how to attain a complex objective (goal) or maximize along a particular dimension over many steps; for example, maximize the points won in a game over many moves. Reinforcement learning solves the difficult problem of correlating immediate actions with the delayed returns they produce. Like humans, reinforcement learning algorithms sometimes have to wait a while to see the fruit of their decisions. They operate in a delayed return environment, where it can be difficult to understand which action leads to which outcome over many time steps.

Importance Weighted Actor-Learner Architecture (IMPALA)

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uses resources more efficiently in single-machine training but also scales to thousands of machines without sacrificing data efficiency or resource utilisation. We achieve stable learning at high throughput by combining decoupled acting and learning with a novel off-policy correction method called V-trace. IMPALA is able to achieve better performance than previous agents with less data, and crucially exhibits positive transfer between tasks as a result of its multi-task approach.

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