[Tex/LaTex] Book option of the combine document class

Question

I included a MWE (a main file and three articles) that uses the combine class with book option. There are two problems. The formatting process creates the LaTeX Error: Environment abstract undefined, and formatting stops at the first \begin{abstract} command in first input file. Press “r” to continue the formatting process. The resulting PDF is almost correct except for the section numbering (0.1, 0.2 … instead of 1, 2 …) in the input article documents. The article documents include the command \setcounter{section}{0} in the preamble. The file formats if I replace book with report, but the section-numbering problem persists. The main document is an accurate example of what I need (A book with parts, several chapters with no input files, and several chapters with input files.) All input files use the article document class. I use MiKTeX 2.9 on Windows 7.

\documentclass[book]{combine}
\usepackage[english]{babel}
\usepackage{blindtext}
\title{The collection}
\author{A. N. Editor}
\begin{document}
\maketitle
\tableofcontents
\part{First part}
\blindtext[1]
\chapter{First chapter}
\section{Introduction}
\blindtext[1]
\chapter{Second chapter}
\section{Introduction}
\ldots
\begin{papers}
    \coltoctitle{First article}
    \coltocauthor{Author of first article}
    \import{inputDoc1}
    \coltoctitle{Second article}
    \coltocauthor{Author of second article}
    \import{inputDoc2}
\end{papers}
\chapter{Third chapter}
\section{Introduction}
\ldots
\begin{papers}
    \coltoctitle{Third article}
    \coltocauthor{Author of third article}
    \import{inputDoc3}    
\end{papers}
\chapter{Chapter 4}
\section{Final introduction}
\end{document} 
%first article
\documentclass[]{article}
\usepackage[english]{babel}
\usepackage{blindtext}
\begin{document}
\title{First article}
\author{Author of first article}
\maketitle
\begin{abstract}
    \blindtext[2]
\end{abstract}
\section{first section}
\blindtext[3]
\end{document}
%second article
\documentclass[]{article}
\usepackage[english]{babel}
\usepackage{blindtext}
\setcounter{section}{0}
\begin{document}
\title{Second article}
\author{Author of second article}
\maketitle
\begin{abstract}
    \blindtext[1]
\end{abstract}
\section{first section}
\blindtext[1]
\end{document}
%third article
\documentclass[]{article}
\usepackage[english]{babel}
\usepackage{blindtext}
\setcounter{section}{0}
\begin{document}
\title{Document 1a}
\author{Author of document 1a}
\maketitle
\begin{abstract}
    \blindtext[3]
\end{abstract}
\section{first section}
\blindtext[1]
\section{second section}
\blindtext[1]
\end{document}

Answer 1

Since you only import articles, and the article document class doesn't define the \chapter the result is that you will have a value of 0 for the chapters of each imported article. As @Papiro pointed, you can avoid the display of chapter counter with \renewcommand*\thesection{\arabic{section}}. However, with that, you lose the format \thechapter.\thesection for the sections in the main document, which in my case would be fine.

Below I present other solution that keeps the format \thechapter.\thesection (without the need to add to add \makeatletter \@ifclassloaded{combine}{\renewcommand*\thesection{\arabic{savechapter}.\arabic{section}}}{}\makeatother at each input articles).

\documentclass[book]{combine}
\usepackage[english]{babel}
\usepackage{blindtext}
\usepackage{filecontents}
\usepackage{etoolbox}
\newcounter{savechapter}
\AtBeginEnvironment{papers}{\setcounter{savechapter}{\value{chapter}}}
\makeatletter
\let\oldimport\import
\renewcommand*{\import}{\renewcommand*\thesection{\arabic{savechapter}.\arabic{section}}\oldimport}
\makeatother

% The input articles
\begin{filecontents*}{inputDoc1.tex}
\documentclass{article}
\usepackage[english]{babel}
\usepackage{blindtext}
\begin{document}
\title{First article}
\author{Author of first article}
\maketitle
\begin{abstract}
\blindtext[2]
\end{abstract}
\section{first section}
\blindtext[3]
\section{Second section}
\end{document}
\end{filecontents*}

\begin{filecontents*}{inputDoc2.tex}
\documentclass{article}
\usepackage[english]{babel}
\usepackage{blindtext}
\begin{document}
\title{Second article}
\author{Author of second article}
\maketitle
\begin{abstract}
\blindtext[1]
\end{abstract}
\section{first section}
\blindtext[1]
\end{document}
\end{filecontents*}

\begin{filecontents*}{inputDoc3.tex}
\makeatother
\documentclass{article}
\usepackage[english]{babel}
\usepackage{blindtext}
\setcounter{section}{1}
\begin{document}
\title{Document 1a}
\author{Author of document 1a}
\maketitle
\begin{abstract}
\blindtext[3]
\end{abstract}
\section{first section}
\blindtext[1]
\section{second section}
\blindtext[1]
\end{document}
\end{filecontents*}

% Define abstract to be used in book class (or use report)
% http://tex.stackexchange.com/questions/51483/how-to-write-abstract-and-acknowledgement-in-book-format
\makeatletter
\if@titlepage
  \newenvironment{abstract}{%
      \titlepage
      \null\vfil
      \@beginparpenalty\@lowpenalty
      \begin{center}%
        \bfseries \abstractname
        \@endparpenalty\@M
      \end{center}}%
     {\par\vfil\null\endtitlepage}
\else
  \newenvironment{abstract}{%
      \if@twocolumn
        \section*{\abstractname}%
      \else
        \small
        \begin{center}%
          {\bfseries \abstractname\vspace{-.5em}\vspace{\z@}}%
        \end{center}%
        \quotation
      \fi}
      {\if@twocolumn\else\endquotation\fi}
\fi
\makeatother


% The main document
\begin{document}
\title{The collection}
\author{A. N. Editor}
\date{\today}
\maketitle

\begin{abstract}
\blindtext[1]
\end{abstract}

\tableofcontents

\part{First part}
\blindtext[1]

\chapter{First chapter}
\section{Introduction}
\blindtext[1]

\chapter{Second chapter}
\section{Introduction}
\ldots
\begin{papers}
    \coltoctitle{First article}
    \coltocauthor{Author of first article}
    \import{inputDoc1}
    \coltoctitle{Second article}
    \coltocauthor{Author of second article}
    \import{inputDoc2}
\end{papers}

\chapter{Third chapter}
\section{Introduction}
\ldots
\begin{papers}
    \coltoctitle{Third article}
    \coltocauthor{Author of third article}
    \import{inputDoc3}    
\end{papers}

\chapter{Chapter 4}
\section{Final introduction}

\end{document}