Undefined control sequence with \delete and the changes package

Question

I keep on getting the following error message when I attempt to compile my source code:

! Undefined control sequence

Before, I was unable to compile and saw another question that had been answered and added

\usepackage{etex}

to my code. Now, upon compiling I get the afforementioned undefined control sequence in reference to a

\delete

Here is a MWE:

\documentclass[a4paper,12pt,twoside]{book}
\usepackage{etex}
\usepackage{amsmath,amssymb,amscd,amsbsy,array,color,epsfig}

\usepackage{changes}

\begin{document}

\chapter{Logic, Set Theory, Functions, and Relations.}
\section{Mathematical Logic.}
\subsection{Introduction.}
\small{Analysis is all about the theory behind Calculus. In this course, we do not take for granted such notions as what the set $\mathbb{R}$ of real numbers is; rather we carefully define $\mathbb{R}$ by `building' it out of other sets - beginning with the set $\mathbb{N}$ of Natural Numbers. Numbers and number systems (i.e. $\mathbb{N}, \mathbb{Z}, \mathbb{Q}, \mathbb{R},$ and $\mathbbC}$) are the `building-blocks' of Analysis. Here in this book, we do not merely state the properties of the Real Number System, but we derive them. \\
However, \deleted[id=MD,remark=blah blah blah]{Would you like any toast?} before we do that (and we shall in Chapter 1), we first \delete[id=MD,remark=blah blah blah]{present}  this introductory chapter - Chapter 0 - in order to give the reader the tools needed to carry on this study of the branch of mathematics known as Analysis. Here, we present a `brief' review of Mathematical Logic, Set Theory, Functions, and Relations; and we `informally' define a few sets of which we shall make frequent use of in Analysis. All of them (or most of them) shall be dealt with more formally in the next chapter.}

\end{document}

I have left out many additional packages I used and since the error occurred so soon in the document I have only shown the first bit of the doc itself. Please forgive me as I have little experience with the changes package, but I thought I was loading it correctly and syntaxing it correctly as well.

Thanks, -MD

Answer 1

Your current document has the following errors or problems:

1. \mathbbC} -> \mathbb{C};

2. changes does not define \delete, only \deleted;

3. You need to define the author/id MD as a "change author" before you can use it, so you need \definechangesauthor[<options>]{MD} after loading \usepackage{changes};

4. It's not advised to use \\ for a paragraph break. Leave a blank line or issue an explicit \par. If you don't enjoy the indentation, see Turn off paragraph indention for a single line. Alternatively, \setlength{\parindent}{0pt} will remove all paragraph indentation in your document.

Here is a complete minimal example:

\documentclass{article}
\usepackage{amssymb,changes}
\definechangesauthor{MD}

\begin{document}

Analysis is all about the theory behind Calculus. In this course, we do not
take for granted such notions as what the set~$\mathbb{R}$ of real numbers 
is; rather we carefully define~$\mathbb{R}$ by `building' it out of other 
sets---beginning with the set~$\mathbb{N}$ of Natural Numbers. Numbers and 
number systems (\textit{i.e.\/}\ $\mathbb{N}$, $\mathbb{Z}$,
$\mathbb{Q}$,~$\mathbb{R}$ and~$\mathbb{C}$) are the `building-blocks' of 
Analysis. Here in this book, we do not merely state the properties of the 
Real Number System, but we derive them.

However, \deleted[id=MD,remark=blah blah blah]{Would you like any toast?} 
before we do that (and we shall in Chapter 1), we first 
\deleted[id=MD,remark=blah blah blah]{present} this introductory 
chapter---Chapter~0---in order to give the reader the tools needed to carry 
on this study of the branch of mathematics known as Analysis. Here, we 
present a `brief' review of Mathematical Logic, Set Theory, Functions, and 
Relations; and we `informally' define a few sets of which we shall make 
frequent use of in Analysis. All of them (or most of them) shall be dealt 
with more formally in the next chapter.

\end{document}