Definition: RL is about learning how to make decisions to
maximize a numerical reward signal without explicit instructions.
Key Features: RL involves trial-and-error exploration and dealing
with delayed rewards, making it distinct from other learning
methods.
2. Three Aspects of RL:
Sensation: The agent must sense its environment's state to
make decisions.
Action: The agent takes actions that influence the environment.
Goal: The agent has explicit goals it aims to achieve.
3. Trade-Off: Exploration vs. Exploitation:
In RL, agents must balance exploration (trying new actions) and
exploitation (using known effective actions) to maximize reward.
4. Interdisciplinary Nature:
RL has strong ties to psychology, neuroscience, mathematics,
and other fields, making it a multidisciplinary approach to
learning.
5. Goal-Directed Interaction:
RL is about complete, interactive, goal-seeking agents
interacting with uncertain environments.
6. Reinforcement Learning vs. Other Learning Paradigms:
RL is distinct from supervised learning (training with labeled
examples) and unsupervised learning (finding hidden structure)
as it focuses on maximizing rewards.
7. Examples of RL:
Examples include chess players using intuition and planning,
adaptive controllers optimizing processes, animals learning and
adapting rapidly, robots making decisions based on battery
levels, and individuals like Phil performing complex, goal-driven
activities.
, Elements of Reinforcement Learning
1. Policy:
Definition: A policy is the learning agent's strategy for
interacting with the environment. It defines how the agent
should behave in response to the perceived states of the
environment.
Example: Imagine a self-driving car. The policy could be a set of
rules and algorithms that dictate how the car should steer,
accelerate, and brake based on sensor data, such as the car's
current position, speed, and the presence of other vehicles on
the road.
Explanation: The policy is like the brain of the agent,
determining its actions based on the information it gathers from
the environment. It can be as simple as predefined rules or as
complex as a neural network that learns the optimal actions
through trial and error.
2. Reward Signal:
Definition: The reward signal provides feedback to the agent by
specifying the immediate benefit or desirability of the agent's
actions in a given state. It quantifies how good or bad an action
is in a specific context.
Example: In a game, the score or points earned after each move
can serve as a reward signal. Positive scores indicate good
moves, while negative scores suggest bad moves.
Explanation: The reward signal guides the agent's learning
process by encouraging actions that lead to higher rewards and
discouraging actions that result in lower rewards. Over time, the
agent aims to maximize cumulative rewards.
3. Value Function: