Lesson 01
Data → feature → model → loss → train → evaluate; train/val/test split; bias-variance trade-off intro.
Lesson 02
y = Xw + b, MSE; closed-form normal equation vs gradient descent; ridge/lasso regularization; R².
Lesson 03
Sigmoid, binary classification, cross-entropy; multi-class softmax; calibration, ROC/AUC.
Lesson 04
Bias-variance trade-off; L1/L2, dropout, early stopping; k-fold CV, nested CV; learning curves.