Further Study
What Next?¶
So far we have only discussed about Supervised models. Supervised learning involves training a model on a labeled dataset, meaning each input comes with the correct output. The goal is for the model to learn to predict these labels on new, unseen data.
Pros:
High accuracy when enough labeled data is available.
Predictable performance and easier to evaluate.
Well-supported with mature libraries.
Cons:
Requires large, clean labeled datasets (can be expensive/time-consuming to produce).
May overfit if not enough data or too complex a model.
Unsupervised models¶
Unsupervised learning works with unlabeled data. The model tries to discover hidden patterns or structures in the data.
Examples: Clustering customers into groups based on purchasing behavior — the model finds structure without being told what group each customer belongs to. Another interesting example is of the autoencoder.
Pros:
Works without labeled data.
Helps with data exploration, dimensionality reduction, and pattern discovery.
Cons:
Hard to evaluate the model (no ground truth).
May find patterns that are not meaningful or useful.
Often requires strong assumptions about data structure.
Example: Autoencoder

Reinforcement Learning¶
Reinforcement learning is based on an agent interacting with an environment. The agent learns through trial and error, receiving rewards or penalties for actions it takes.
Example: Training a robot to walk or a program to play chess — it learns strategies that maximize short or long-term reward.
Pros:
Excellent for sequential decision-making and control tasks.
Learns directly from interaction without needing labeled datasets.
Cons:
Often slow and computationally expensive.
May require a lot of exploration or simulation before learning effectively.
Sensitive to the choice of reward structure.

Figure 1:Image: Florian Marquardt lecture notes (https://