How to reduce the space between the author block and paper text? sig-alternate.cls

Question

I am using the template sig-alternate.cls, but I find that the space between the author block and the paper text is too large, how can I reduce this space?

Edit: I want to reduce the space between the author block and the paper text.

\documentclass{sig-alternate}
\begin{document} 
\title{shrink space}
\author{XXX}
\maketitle
paper text here!
\end{document}

Answer 1

Your document class defines the command \@maketitle with an extra vertical skip. Use the following definition to reduce the space:

\def\@maketitle{\newpage
 \null
 \setbox\@acmtitlebox\vbox{%
\baselineskip 20pt
\vskip 2em                   % Vertical space above title.
   \begin{center}
    {\ttlfnt \@title\par}       % Title set in 18pt Helvetica (Arial) bold size.
    \vskip 1.5em                % Vertical space after title.
%This should be the subtitle.
{\subttlfnt \the\subtitletext\par}\vskip 1.25em%\fi
    {\baselineskip 16pt\aufnt   % each author set in \12 pt Arial, in a
     \lineskip .5em             % tabular environment
     \begin{tabular}[t]{c}\@author
     \end{tabular}\par}
    \vskip 1.5em               % Vertical space after author.
   \end{center}}
 \dimen0=\ht\@acmtitlebox
% \advance\dimen0 by -12.75pc\relax % comment by Marco Daniel
 \unvbox\@acmtitlebox
 \ifdim\dimen0<0.0pt\relax\vskip-\dimen0\fi}

---

Without the modification:

With the modification:

Here the complete MWE:

\documentclass{sig-alternate}
\usepackage{kantlipsum}
\makeatletter
\def\@maketitle{\newpage
 \null
 \setbox\@acmtitlebox\vbox{%
\baselineskip 20pt
\vskip 2em                   % Vertical space above title.
   \begin{center}
    {\ttlfnt \@title\par}       % Title set in 18pt Helvetica (Arial) bold size.
    \vskip 1.5em                % Vertical space after title.
%This should be the subtitle.
{\subttlfnt \the\subtitletext\par}\vskip 1.25em%\fi
    {\baselineskip 16pt\aufnt   % each author set in \12 pt Arial, in a
     \lineskip .5em             % tabular environment
     \begin{tabular}[t]{c}\@author
     \end{tabular}\par}
    \vskip 1.5em               % Vertical space after author.
   \end{center}}
 \dimen0=\ht\@acmtitlebox
% \advance\dimen0 by -12.75pc\relax % comment by Marco Daniel
 \unvbox\@acmtitlebox
 \ifdim\dimen0<0.0pt\relax\vskip-\dimen0\fi}
\makeatother

\begin{document} 
\title{shrink space}
\author{XXX}
\maketitle
\kant
\end{document}

Answer 2

I think the following method is a more direct way: comment out this line in the sig-alternate.cls.

\advance\dimen0 by -12.75pc\relax % Increased space for title box -- KBT

This line is in the definition of \@maketitle, and is meant to increase the space between the author block and paper text.