Second cascade of Vol II PDF Linux failure after PR #1500. LuaLaTeX fails on \subitem & compute optimality with "Misplaced alignment tab character &".
Root cause: introduction.qmd:1002 — \index{Scaling Laws!& compute optimality} has a literal &. makeindex passes it through; LaTeX panics on the unescaped alignment tab.
Fix: drop the & from the subentry.
Test plan
Pre-commit passes
Comprehensive scan (balanced-brace + ignore \...\\) book-wide found only this one entry with a bare &/%/#/bare _/bare ^ in a key
Book Validate (Dev) passes on this PR merge
🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.
## 📋 Pull Request Information
**Original PR:** https://github.com/harvard-edge/cs249r_book/pull/1501
**Author:** [@profvjreddi](https://github.com/profvjreddi)
**Created:** 4/23/2026
**Status:** ✅ Merged
**Merged:** 4/23/2026
**Merged by:** [@profvjreddi](https://github.com/profvjreddi)
**Base:** `dev` ← **Head:** `fix/book-vol2-index-ampersand`
---
### 📝 Commits (1)
- [`bfb8030`](https://github.com/harvard-edge/cs249r_book/commit/bfb80305f3db0a0177080475c7ccec039dd6ab0a) fix(book/vol2): escape LaTeX ampersand bug in scaling laws index entry
### 📊 Changes
**1 file changed** (+1 additions, -1 deletions)
<details>
<summary>View changed files</summary>
📝 `book/quarto/contents/vol2/introduction/introduction.qmd` (+1 -1)
</details>
### 📄 Description
## Summary
Second cascade of Vol II PDF Linux failure after PR #1500. LuaLaTeX fails on `\subitem & compute optimality` with "Misplaced alignment tab character &".
**Root cause**: [introduction.qmd:1002](book/quarto/contents/vol2/introduction/introduction.qmd#L1002) — `\index{Scaling Laws!& compute optimality}` has a literal `&`. makeindex passes it through; LaTeX panics on the unescaped alignment tab.
**Fix**: drop the `&` from the subentry.
## Test plan
- [x] Pre-commit passes
- [x] Comprehensive scan (balanced-brace + ignore \\$...\\$) book-wide found only this one entry with a bare `&`/`%`/`#`/bare `_`/bare `^` in a key
- [ ] Book Validate (Dev) passes on this PR merge
---
<sub>🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.</sub>
Blocking a user prevents them from interacting with repositories, such as opening or commenting on pull requests or issues. Learn more about blocking a user.
📋 Pull Request Information
Original PR: https://github.com/harvard-edge/cs249r_book/pull/1501
Author: @profvjreddi
Created: 4/23/2026
Status: ✅ Merged
Merged: 4/23/2026
Merged by: @profvjreddi
Base:
dev← Head:fix/book-vol2-index-ampersand📝 Commits (1)
bfb8030fix(book/vol2): escape LaTeX ampersand bug in scaling laws index entry📊 Changes
1 file changed (+1 additions, -1 deletions)
View changed files
📝
book/quarto/contents/vol2/introduction/introduction.qmd(+1 -1)📄 Description
Summary
Second cascade of Vol II PDF Linux failure after PR #1500. LuaLaTeX fails on
\subitem & compute optimalitywith "Misplaced alignment tab character &".Root cause: introduction.qmd:1002 —
\index{Scaling Laws!& compute optimality}has a literal&. makeindex passes it through; LaTeX panics on the unescaped alignment tab.Fix: drop the
&from the subentry.Test plan
...\\) book-wide found only this one entry with a bare&/%/#/bare_/bare^in a key🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.