Different numbering scheme for chapters in different parts

Question

I'm writing a book using amsbook. The book is divided into two parts: a part called "Basic topics" that roughly speaking corresponds to a course I teach, and a part called "Essays" that contains a number of loosely related essays giving applications, extensions, etc of the basic topics.

I would like to have these numbered independently, with the chapters numbered with numbers and the essays numbered with letters. Here's what I mean:

• Part 1: Basic topics
• Chapter 1: chapter title
• Chapter 2: chapter title
• ...
• Chapter n: chapter title
• Part 2: Essays
• Essay A: essay title
• Essay B: essay title
• ...
• Essay Z: essay title

I can change the behavior of chapters at the start of Part 2 to make them called "essays" and to have them enumerated using letters instead of numbers, but then they don't start with A but rather with the letter corresponding to n+1, where n is the number of the last chapter in Part 1. If I reset the counter, all the internal hyperlinks get screwed up.

Here is a minimal working example:

\documentclass{amsbook}

\usepackage{etoolbox}
\makeatletter
\patchcmd\@part{\protect\enspace\protect\noindent}{\hspace{.5em}}{}{\ERROR}
\makeatother

\usepackage{hyperref}

\theoremstyle{plain}
\newtheorem{theorem}{Theorem}[section]

\begin{document}

\part{Basic topics}

\chapter{First chapter name}

\chapter{Second chapter name}

\part{Essays}
\renewcommand{\chaptername}{Essay}
\renewcommand{\thechapter}{\Alph{chapter}}
\setcounter{chapter}{0}

\chapter{First essay name}

\end{document}

When this compiles, hyperref throws a warning that there is a "destination with the same identifier". If I delete the line "\setcounter{chapter}{0}" it screws up the lettering of the essays.

Answer 1

The hyperlinks for chapter 1 and essay A work for me.

\documentclass{amsbook}
\usepackage{hyperref}

\begin{document}
\tableofcontents

\part{book}
\chapter{book stuff}
\part{essays}
\setcounter{chapter}{0}
\renewcommand{\chaptername}{Essay}
\renewcommand{\thechapter}{\Alph{chapter}}
\renewcommand{\theHchapter}{\Alph{chapter}}
\chapter{on a lump of putty found in my armpit one summer's morning}
\end{document}