Nathan Lambert
Nathan Lambert
@natolambert·8K subscribers·27 videos

Q&A 2: Mastering the Derivations, Running Algorithms at Home & Notation Gotcha's | RLHF Course

Posted

July 1, 2026

Views

644

Likes

22

Comments

1

Engagement

3.57%

Search the Record

Indexed

Every word spoken in this episode is indexed. Type any phrase to jump straight to the moment it was said.

Type any word or phrase that may have been spoken. Click a result to seek the player to that exact moment.

Try a name, a topic, or a quoted line

Chapters

YouTube Description

as posted by the channel

Catching up on user questions and making sure we dot all the i's and cross the t's in the course. This is all about going deeper on the derivations and notation of doing post-training right. Plus, a bunch of links to more resources (again).

Welcome to The RLHF Book & Post-Training Course with Nathan Lambert.

Ask questions and I'll answer them in the next roundup video!

Slides for this lecture are here

Chapters:

Estimating KL in practice John Schulman's k1/k2/k3 note (essential KLpenalty lore)

Suggested Experiments (each chapter: runnable code + knobs to vary):

• Ch 4 · Instruction tuning

• Ch 5 · Reward models

• Ch 6 · Policy gradients

• Ch 8 · Direct alignment (DPO/IPO easiest start)

• Ch 9 · Rejection sampling

Interactive modelcomparison library (see each posttraining stage on the same prompt)

All resources will be available at

Order a copy of the book (physical recommended) on Manning.com

Order a copy on Amazon

With specific course resources at (recording links, slides in PDF and native form, etc.)

And code at

Get more information on Nathan at and stay up to date with his work on Interconnects

Course YouTube playlist

Join the book's Discord Community

Nathan is on…

Slides are built with Colloquium

Thank you to my many collaborators who helped me learn this information I get to share with the world!

Guests & Subjects Covered

Q&A 2The RLHF BookPost-Training CourseNathan Lambert AskChapters DerivationExtra RLEstimating KLJohn Schulman's

Sentinel Indexing in Progress

Metadata and chapters are available. Claim extraction for this episode is pending.

All video content is delivered via YouTube embedded players in accordance with the YouTube Terms of Service. Sentinel provides research tools that promote discovery and accountability across political media.