This episode addresses how Reinforcement Learning from Human Feedback (RLHF) adds the final layer of alignment after supervised fine-tuning, shifting the training signal from “right vs wrong” to “better vs worse.” We explore how preference rankings create a reward signal (reward models plus PPO) and the newer shortcut (DPO) that learns preferences directly, then connect RLHF to safety through the Helpful, Honest, Harmless goal. We also unpack the “alignment tax,” the trade-off between being safe and being genuinely useful, and close by setting up the next module on running models at scale, starting with GPU memory limits, plus a personal reflection on starting later without being behind.

This episode addresses how we turn a raw base model into something that behaves like a real assistant using Supervised Fine-Tuning (SFT). We explore instruction and response training data, why SFT makes behaviors consistent beyond prompting, and the practical engineering choices that keep fine-tuning efficient and safe, including low learning rates and LoRA-style adapters. By the end, you will understand what SFT solves, and why the next layer (RLHF) is needed to add human preference and nuance.

This episode addresses the physical and mathematical limits of a model’s "short-term memory." We explore the context window and the engineering trade-offs required to process long documents. You will learn about the quadratic cost of attention where doubling the input length quadruples the computational work and why this creates a massive bottleneck for long-form reasoning. We also introduce the architectural tricks like Flash Attention that allow us to push these limits further. By the end, you will understand why context is the most expensive real estate in the generative stack.