A single linear hyperplane cannot separate diagonals (XOR). A 2-layer MLP transforms the feature space into curved non-linear decision regions.
Computes \( \hat{y} = \sigma(w_1 x_1 + w_2 x_2 + b) \). Perfect for clean linearly separable data, but fails on complex manifold topologies.
k-NN creates Voronoi-like local decision pockets without weights. Decision trees create orthogonal axis-aligned partition boxes.
Too small \(\eta\) leads to glacial convergence; too high \(\eta\) oscillates wildly across loss ravines. Observe how loss trajectories morph.