machine-learning.md

Machine Learning

Machine learning is the science of getting computers to act without being explicitly programmed.

• Learn from data;
• Improve performance with experience;
• There are multiple types of machine learning:
  • Supervised learning;
  • Unsupervised learning;
  • Self-supervised learning;
  • Reinforcement learning;
  • Active learning.

Steps of a machine learning:

1. Formulate the problem;
2. Collect and clean the data;
3. Learn a model;
4. Evaluate the model.

Notation

• Input: $x \in X$;
• Output: $y \in Y$;

Types of Learning

• Supervised learning: pairs $(x, y)$ are provided at training time;
  • Classification - binary or multi-class;
  • Regression;
• Unsupervised learning: only $x$ is provided at training time;
  • Clustering;
  • Pattern mining;
  • Dimensionality reduction;
• Self-supervised learning: $x$ is provided at training time, but it is generated from $y$;
• Reinforcement learning: the agent interacts with the environment and receives rewards;
• Active learning: the learner can query the teacher to obtain the label of a data point.