# Recent Advances in Hierarchical Reinforcement Learning

@article{Barto2003RecentAI, title={Recent Advances in Hierarchical Reinforcement Learning}, author={Andrew G. Barto and Sridhar Mahadevan}, journal={Discrete Event Dynamic Systems}, year={2003}, volume={13}, pages={41-77} }

Reinforcement learning is bedeviled by the curse of dimensionality: the number of parameters to be learned grows exponentially with the size of any compact encoding of a state. Recent attempts to combat the curse of dimensionality have turned to principled ways of exploiting temporal abstraction, where decisions are not required at each step, but rather invoke the execution of temporally-extended activities which follow their own policies until termination. This leads naturally to hierarchical…

## 1,045 Citations

### Learning state and action space hierarchies for reinforcement learning using action-dependent partitioning

- Computer Science
- 2006

This dissertation reviews several approaches to temporal abstraction and hierarchical organization that machine learning researchers have recently developed and presents a new method for the autonomous construction of hierarchical action and state representations in reinforcement learning, aimed at accelerating learning and extending the scope of such systems.

### Efficient Reinforcement Learning with Hierarchies of Machines by Leveraging Internal Transitions

- Computer ScienceIJCAI
- 2017

A new hierarchical reinforcement learning algorithm is proposed that automatically discovers many internal transitions where a machine calls another machine with the environment state unchanged, and shortcircuits them recursively in the computation of Q values.

### Automatic abstraction controller in reinforcement learning agent via automata

- Computer ScienceAppl. Soft Comput.
- 2014

### Hierarchical Reinforcement Learning: A Survey and Open Research Challenges

- Computer ScienceMach. Learn. Knowl. Extr.
- 2022

This survey paper introduces a selection of problem-specific approaches, which provided insight in how to utilize often handcrafted abstractions in specific task settings, and introduces the Options framework, which provides a more generic approach, allowing abstractions to be discovered and learned semi-automatically.

### Fast reinforcement learning with generalized policy updates

- Computer ScienceProceedings of the National Academy of Sciences
- 2020

It is argued that complex decision problems can be naturally decomposed into multiple tasks that unfold in sequence or in parallel, and associating each task with a reward function can be seamlessly accommodated within the standard reinforcement-learning formalism.

### Optimal Time Scales for Reinforcement Learning Behaviour Strategies

- Computer Science
- 2010

This thesis derives gradient descent-based algorithms for learning optimal termination conditions of options, based on a new option termination representation, and incorporates the proposed approach into policy-gradient methods with linear function approximation.

### Masters Thesis: Hierarchical Reinforcement Learning for Spatio-temporal Planning

- Computer Science
- 2018

A novel algorithm for learning this hierarchical structure of a discrete-state goaloriented Factored-MDP (FMDP) is proposed in the thesis work taking into account the causal structure of the problem domain with the use of Dynamic Bayesian Network (DBN) model.

### On Efficiency in Hierarchical Reinforcement Learning

- Computer ScienceNeurIPS
- 2020

This paper formalizes the intuition that HRL can exploit well repeating "subMDPs", with similar reward and transition structure, and establishes conditions under which planning with structure-induced options is near-optimal and computationally efficient.

### A Deep Hierarchical Reinforcement Learning Algorithm in Partially Observable Markov Decision Processes

- Computer ScienceIEEE Access
- 2018

This paper proposes a hierarchical deep reinforcement learning approach for learning in hierarchical POMDP in which the tasks have only partial observability and possess hierarchical properties and proposes the deep hierarchical RL algorithm.

### Why Does Hierarchy (Sometimes) Work So Well in Reinforcement Learning?

- Computer Science, PsychologyArXiv
- 2019

This work isolates and evaluates the claimed benefits of hierarchical RL on a suite of tasks encompassing locomotion, navigation, and manipulation and finds that most of the observed benefits of hierarchy can be attributed to improved exploration, as opposed to easier policy learning or imposed hierarchical structures.

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