Deep Learning

Work in progress: this part of the notes is still being revised.

Deep Learning develops the networks that learn their own features: how they are built, why they can be trained, how they generalize despite fitting their training data, and how they are made to work in practice and at scale. It builds on the differentiation, optimization, and PyTorch interfaces of Foundations and on the losses, regularization, model selection, and kernels of Machine Learning. Twelve core chapters follow the main topics of the reading plan, and three optional chapters cover its extensions.

Chapters

ChapterMain contentReading plan
1. Deep Feedforward NetworksLearned features; the multilayer perceptron and backpropagation in practice; activation functions; universal approximation and its limits; depth separations and linear regions; output layers and losses; nonconvexity and symmetry.Topic 1
2. Initialization and Signal PropagationForward and backward variance recursions; Glorot and He initialization; saturation; correlations between inputs and the ReLU correlation map; Jacobian spectra and dynamical isometry; dead units.Topic 2
3. Optimization for Deep NetworksMinibatch noise, the gradient noise scale, and the critical batch size; learning-rate schedules and warmup; curvature, the stability threshold, and the edge of stability; adaptive and second-order methods; saddles, plateaus, and mode connectivity.Topic 3
4. Normalization and Residual ConnectionsBatch, layer, RMS, and group normalization; scale invariance and the effective learning rate; residual connections, the scale of the residual stream, and identity initializations; pre- and post-normalization.Topic 4
5. Regularization and Generalization in Deep NetworksMemorization of random labels; double descent; weight decay, dropout, augmentation, label smoothing, and early stopping; ensembles and weight averaging; implicit bias, flat minima, and benign overfitting.Topic 5
6. Convolutional NetworksLocality and weight sharing; the convolution operation, padding, stride, and dilation; equivariance, pooling, and aliasing; receptive fields; convolution as a matrix product and its cost.Topic 6
7. Convolutional Architectures and Transfer LearningFrom LeNet to ConvNeXt; bottlenecks, residual and efficient blocks; compound scaling and training recipes; pretrained features, linear probes, and fine-tuning.Topic 7
8. Recurrent NetworksRecurrence and weight sharing over time; backpropagation through time and vanishing gradients; LSTM and GRU; encoder–decoder models and teacher forcing; temporal convolutions and state-space models.Topic 8
9. Attention and TransformersAttention as kernel smoothing; scaled dot-product and multi-head self-attention; masks; position encodings and RoPE; the transformer block and its three families; efficient and approximate attention; vision transformers.Topic 9
10. Self-Supervised Representation LearningPretext tasks; linear autoencoders and PCA; denoising; contrastive learning, InfoNCE, and mutual information; collapse and methods without negatives; masked modeling; evaluating representations.Topic 10
11. Training at Scale and Efficient InferenceThe roofline model and fusion; floating-point formats and mixed precision; memory accounting and checkpointing; data, sharded, tensor, and pipeline parallelism; quantization, pruning, and distillation.Topic 11
12. Practical MethodologyA workflow and sanity checks; reading learning curves and internal statistics; the learning-rate range test; hyperparameter search strategies; seed variance, silent bugs, and reproducibility.Topic 12
13. Graph Neural Networks (optional)Permutation symmetry; message passing; graph convolutional and attention networks; the Weisfeiler–Lehman bound; oversmoothing and oversquashing.Topic 13
14. Detection and Segmentation (optional)IoU and average precision; two-stage, one-stage, and anchor-free detectors; the focal loss; DETR and set prediction; fully convolutional networks, U-Net, and transposed convolutions; instance and promptable segmentation.Topic 14
15. Infinite Width and the Neural Tangent Kernel (optional)Wide networks as Gaussian processes; linearization and the neural tangent kernel; training as kernel regression; spectral bias; lazy and feature-learning regimes; μP.Topic 15

Chapters 1–5 treat the deep feedforward network as a trainable object: what it can represent, how its initialization, optimizer, normalization, and residual connections make training possible, and why it generalizes. Chapters 6–9 develop the architectures that build structure into the network, convolution for images, recurrence for sequences, and attention for everything. Chapters 10–12 turn to representations learned without labels, to the engineering of training and serving large models, and to the practice of making a network work. The optional chapters extend the architectures to graphs and to dense prediction and give the infinite-width theory. Proofs and longer derivations appear in collapsed appendices at the end of each chapter.

Shared conventions

Examples and supporting resources

The chapter text contains the definitions, derivations, and worked examples, and every figure is generated by a script in Sources/Figure code. The computing setup records the Python environment and how to regenerate the figures, and figure sources records the data and construction behind each figure.

The reading plan lists the lectures and readings for each topic. Course links collects the courses and practical guides it draws on, video links the lecture recordings by chapter, books and documentation the reference texts and library guides, and papers the principal research behind each chapter. The UMich EECS 498-007 assignments implement fully connected, convolutional, recurrent, and attention networks from scratch in PyTorch with automatic checks, and the UNIGE course page provides practical sessions with solutions; both fit the chapters directly.

Connections to later modules

Artificial intelligence treats search, planning, logic, and probabilistic reasoning, the parts of intelligent behavior that are not learned end to end. Networks from this module appear there as learned heuristics and evaluation functions. The AI overview lists its chapters.

NLP and large language models build directly on the transformer of chapter 9, the self-supervised pretraining of chapter 10, and the training at scale of chapter 11: tokenization, language-model pretraining, scaling laws, fine-tuning, and in-context learning.

Generative AI extends the autoencoders and denoising of chapter 10 to variational autoencoders and diffusion models, and adds adversarial networks and normalizing flows; its image models use the U-Net of chapter 14 and the transformers of chapter 9.

Reinforcement learning uses networks as value functions and policies. Its instabilities, from nonstationary targets to exploding value estimates, are diagnosed with the tools of chapters 2–4 and 12.

Safety and frontier research studies what trained networks compute and whether they can be trusted: mechanistic interpretability starts from the residual stream and attention heads of chapter 9, and the theory of deep learning continues from the generalization puzzles of chapter 5 and the infinite-width limits of chapter 15.

Reading plan and sources