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Trade-off Between Exploration and Exploitation, and Epsilon(ε-) Greedy Exploration
- Python Automation and Machine Learning for ICs -
- An Online Book -
Python Automation and Machine Learning for ICs                                                           http://www.globalsino.com/ICs/        


Chapter/Index: Introduction | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Appendix

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In reinforcement learning, the trade-off between trying out new actions to discover their effects (exploration) and choosing actions that are known to yield good rewards based on past experience (exploitation) is a crucial aspect of learning. Striking the right balance between exploration and exploitation is a key challenge in reinforcement learning. Common strategies to balance exploration and exploitation include:

  • Epsilon-Greedy Strategy: With a probability , choose a random action (explore), and with probability , choose the action with the highest estimated value (exploit).

  • Softmax Exploration: Use a softmax function to assign probabilities to actions based on their estimated values. This strategy allows for a smooth transition between exploration and exploitation.

  • Upper Confidence Bound (UCB): Select actions based on an upper confidence bound on their estimated values. This method encourages exploration by giving higher uncertainty actions a chance to be selected.

  • Thompson Sampling: Sample actions according to their probabilities of being optimal, updating these probabilities based on observed outcomes.

Epsilon-greedy exploration is a strategy used in reinforcement learning and multi-armed bandit problems to balance exploration and exploitation. The basic idea is to choose the action that currently seems to be the best most of the time (exploitation), but with a small probability, epsilon (ε), choose a random action instead (exploration). The value of ε is a hyperparameter that determines the balance between exploration and exploitation. If ε is set to a high value, the algorithm will explore more, potentially discovering better actions, but it might sacrifice short-term gains by not exploiting the current best action. If ε is set to a low value, the algorithm will exploit more, focusing on the currently best-known action, but it might miss out on discovering better actions. The range of values for ε typically falls between 0 and 1. Specifically, ε is a probability, so its values are constrained to the interval [0, 1]. The epsilon-greedy strategy uses this parameter to determine the probability of exploration versus exploitation.

  • When ε is 0, the algorithm performs pure exploitation, always choosing the action with the highest estimated value.

  • When ε is 1, the algorithm performs pure exploration, always choosing a random action regardless of its estimated value.

  • For values of ε between 0 and 1, the algorithm combines both exploration and exploitation based on the specified probability. For example, if ε is set to 0.1, there is a 10% chance of exploration and a 90% chance of exploitation on each decision.

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