Lessons
About this phase
You now know how a transformer computes. This phase is about the systems built on top of it: how a raw next-token predictor becomes a helpful assistant (pretraining → supervised fine-tuning → preference optimization and RL), how to adapt models cheaply with LoRA, how to prompt and decode them well, how reasoning models spend compute at test time, and how to evaluate any of it honestly. The second half opens the generative-modeling toolbox beyond text — VAEs, GANs, diffusion and flow matching, and multimodal models that join images, audio and language — then looks inside the network with mechanistic interpretability and closes with safety, risk and a hands-on fine-tuning project. Every lesson keeps the math explicit, from the ELBO to the DPO loss to classifier-free guidance.
By the end you can
- Explain the three-stage LLM lifecycle and read a model card or technical report critically
- Derive and implement LoRA, and choose between prompting, RAG and fine-tuning for a given problem
- Write down and explain the RLHF objective, the DPO loss and GRPO's advantage estimate
- Control generation with temperature, top-k/top-p and constrained decoding, and know what each does to the distribution
- Derive the VAE ELBO and the diffusion training objective, and sample from a diffusion or flow-matching model
- Design an evaluation that survives contamination and judge bias, and apply a safety checklist to an LLM product