Grazie Enrico! Ho scoperto che il problema era il file mythesis.cls, che contiene le informazioni per l’impaginazione della tesi: ho provato, infatti, a sostituirlo con la classe book e l’indice viene generato! Certo poi cambia un po’ l’impaginazione e le prime due pagine, contenenti il titolo, logo dell’università etc., non ci sono, però posso sempre scrivere tutta la tesi usando mythesis e poi usare book per fare solo l’indice. Comunque, anche solo per curiosità, questo è il contenuto di mythesis.cls:
%
% This file is copyright (C) 2003 Sam Noble. It may be modified so long
% as my name is not removed and the modifier adds his name to the file.
% Redistribution permitted.
%
% Class file, Sam Noble 12/04/2001
% Title Page, David Perkinson 09/03/1995
% Acknowledgements Page, David Perkinson & Sam Noble
%
% Modificato da Otello Maria per la sua bella tesi!
% Colonna, 30/09/2003\NeedsTeXFormat{LaTeX2e}
\ProvidesClass{mythesis}[30/09/2003 LaTeX Thesis Class]
\DeclareOption*{\PassOptionsToClass{\CurrentOption}{book}}
\ProcessOptions\relax
\LoadClass{book}
\PassOptionsToPackage{nottoc}{tocbibind}
\RequirePackage{tocbibind}
\RequirePackage{fancyhdr}% This gives us rules below the headers
\AtBeginDocument{%
\fancyhf{}
\fancyhead[LE,RO]{\thepage}
\fancyhead[RE]{\slshape \leftmark}
\fancyhead[LO]{\slshape \rightmark}
\pagestyle{fancy}
}% Stolen from book.cls and modified
\let\RToldchapter\chapter
\renewcommand{\chapter}{\if@openright\RTcleardoublepage
\else\clearpage\fi
\thispagestyle{empty}
\global \@topnum\z@
\@afterindentfalse
\secdef\@chapter\@schapter}\newcommand{\RTcleardoublepage}{
\clearpage\if@twoside \ifodd\c@page\else
\thispagestyle{empty}\hbox{}\newpage
\if@twocolumn\hbox{}\newpage\fi\fi\fi}\let\RToldcleardoublepage\cleardoublepage
\renewcommand{\cleardoublepage}{\RTcleardoublepage}% adjust margins for binding
\setlength{\oddsidemargin}{.6in}
\setlength{\evensidemargin}{0in}
\setlength{\textwidth}{5.9in}
\setlength\topmargin{0in}
\addtolength\headheight{2.5pt}
\addtolength\topmargin{-\headheight}
\addtolength\topmargin{-\headsep}
\addtolength\textheight{1in}
\addtolength\textheight{\headheight}
\addtolength\textheight{\headsep}\def\division#1{\gdef \@division{#1}}
\def\@division{\@latex@warning@no@line{No \noexpand\division given}}% le mittiche correzioni di Otello Maria: mittico!
\def\relatore#1{\gdef \@relatore{#1}}
\def\@relatore{\@latex@warning@no@line{No \noexpand\relatore given}}
\def\correlatore#1{\gdef \@correlatore{#1} \@correlatoretrue}
\global\let\@correlatore\@empty
\newif\if@correlatore
\@correlatorefalse
\renewcommand{\chaptername}{Capitolo}
\renewcommand{\contentsname}{Indice}
\renewcommand{\figurename}{Figura}
\renewcommand{\bibname}{Bibliografia}
\renewcommand{\appendixname}{Appendice}\renewcommand\l@chapter[2]{%
\ifnum \c@tocdepth >\m@ne
\addpenalty{-\@highpenalty}%
\vskip 1.0em \@plus\p@
\setlength\@tempdima{1.5em}%
\begingroup
\parindent \z@ \rightskip \@pnumwidth
\parfillskip -\@pnumwidth
\leavevmode \bfseries
\advance\leftskip\@tempdima
\hskip -\leftskip
#1\nobreak\normalfont
\leaders\hbox{$\m@th \mkern \@dotsep mu\hbox{.}\mkern \@dotsep mu$}\hfill
\nobreak\hb@xt@\@pnumwidth{\bfseries \hss #2}\par
\penalty\@highpenalty
\endgroup
\fi}\newenvironment{abstract}{%
\if@twocolumn
\@restonecoltrue\onecolumn
\else
\@restonecolfalse
\fi
\chapter[Abstract]{}
\begin{center}
{\fontsize{14}{16}\selectfont \bfseries Abstract}
\end{center}
\fontsize{12}{14}\selectfont
}{\clearpage \if@restonecol\twocolumn\fi}%\ifx\pdfoutput\@undefined
\newcommand{\RTpercent}{\@percentchar\space}
\AtBeginDvi{\special{!\RTpercent HotHello’s LaTeX Thesis, August-September 2003}}
\AtBeginDvi{\special{rawpostscript \RTpercent HotHello’s LaTeX Thesis, August-September 2003}}
\else
\AtEndDocument{\pdfinfo{/Creator(HotHello’s LaTeX Thesis, August-September 2003)}}
\fi\renewcommand{\maketitle}{
{\pagestyle{empty}
\fontsize{12}{14}\selectfont
\begin{titlepage}
\newpage
\let\footnotesize\small
\let\footnoterule\relax
\let \footnote \thanks
\baselineskip = 1.4\baselineskip
\setbox0=\hbox{of the Requirements for the Degree}
\begin{center}
\setcounter{page}{1}
\vfil
\centerline{\hbox to \wd0 {\hbox{}\hrulefill\hbox{}}}
Universit\`a degli studi di Roma \\
“La Sapienza”\\
\begin{figure}[h]
\centering
\includegraphics[width=18mm]{logo}
\end{figure}
Facolt\`a di Scienze Matematiche Fisiche e Naturali \\
\@division \\
\centerline{\hbox to \wd0 {\hbox{}\hrulefill\hbox{}}}
\null\vfil
{\fontsize{16}{21}\selectfont \@title}
\vfil
\bigskip
{\fontsize{14}{18}\selectfont
\centerline{\hbox to \wd0 {\hbox{}\hrulefill\hbox{}}}
\@author \\
\@date\par}
\centerline{\hbox to \wd0 {\hbox{}\hrulefill\hbox{}}}
\bigskip
{\fontsize{14}{18}
\vfil
\bigskip
\begin{tabular}{c c c c}
\textsl{Relatore} & \medskip & & \textsl{Correlatore}\\
\textrm{\@relatore} & \medskip & ~ ~ ~ ~ ~ ~ & \textrm{\@correlatore} \\
\end{tabular}
\par}
\end{center}\par
\end{titlepage}
\cleardoublepage}
}
[/quote]