Numbers and sources

This book makes one promise: every number is real. These are the rules followed while writing it.

Numbers

1. A number from our own experiment is written only from an experiment that was actually run, and the run’s exact output is saved next to the script as output.txt. It comes with the MuJoCo (or library) version, the hardware, and whether the experiment is deterministic.
2. A number from someone else (a config line, a document, a paper) comes with its link. Primary sources are preferred: the code itself, official docs, the paper.
3. The result of an experiment that hasn’t been run is never written. Pages marked “coming soon” contain only the plan.
4. Wherever a success rate is stated, the number of trials is stated too. From lesson 25 on, a confidence interval is given as well.
5. A claim that can’t be verified is either removed or clearly marked “unverified”.

Simulation and reality

• Simulation results are written as “in simulation”. If the real-world counterpart wasn’t measured, we don’t say “it’s the same in reality”.
• The output of a model (e.g. MuJoCo’s air-drag model) is not presented as a measurement.
• A real robot’s training numbers and the numbers used on the real robot are kept apart (see lesson 12: 20 / 0.5 in training, 60 / 5 in the real Go2 example).

Source types

Mark	Meaning
Primary	The code, document or paper itself was read
Secondary	Third-party summary, news, search result. Only if no primary source is found, and labelled as such
Unverified	The source couldn’t be reached, or it doesn’t say this. Not used as a claim in the text

Copyright

• Robot models come from MuJoCo Menagerie under their own licenses (e.g. robotstudio_so101 Apache-2.0, unitree_go2 BSD-3-Clause). Images are our own renders.
• Manufacturer names are used factually; no manufacturer endorses or approves this book.
• No long quotes from other sources; short quotes come with their source.