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Short note: supervised vs unsupervised

Short answer

Supervised learning uses labelled data to predict outputs (e.g., classification), while unsupervised learning finds hidden patterns in unlabelled data (e.g., clustering). Supervised has error feedback; unsupervised has no teacher.

Write a short note on supervised versus unsupervised learning.

Supervised learning trains a model on labelled data, where each input has the correct output (target). The model learns the mapping and the error between prediction and target is used to adjust it. Tasks: classification (spam / not spam) and regression (house price). Algorithms: perceptron, back-propagation, decision trees, SVM, k-NN.

Unsupervised learning works on unlabelled data. The model finds hidden structure by itself, such as clusters, similarities or lower-dimensional representations. Tasks: clustering, association, dimensionality reduction. Algorithms: k-means, Kohonen SOM, competitive learning, PCA.

PointSupervisedUnsupervised
DataLabelledUnlabelled
Teacher/feedbackYes (error signal)No
GoalPredict outputDiscover patterns
Accuracy checkEasy, against known labelsHard, no ground truth
ExampleHandwritten digit recognitionCustomer segmentation

A third type, reinforcement learning, learns from rewards and penalties.

✓ Answer checked by Claude Opus 5.5 (high effort)

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