\begin{table}%t7
\caption{\label{individual_vs_mean}Slopes of the Arches cluster IMF derived from average dereddening are shown in the two first rows.} 
\small%\centerline
 {
\begin{tabular}{c c c c } 
\hline\hline
\quad  & $r < 0.2$ pc &  $0.2 < r < 0.4$ pc & $r < 0.4$ pc \\
\hline
$\Gamma^{a}$  &$-0.60\pm0.17$ & $-1.15\pm0.20$    &$-0.81\pm0.19$ \\ 
$\Gamma^{b}$  &$-0.60\pm0.17$ & $-1.23\pm0.23$    &$-0.96\pm0.24$ \\ 
$\Gamma^{c}$  &$-0.88\pm0.20$ & $-1.28\pm0.20$    &$-1.1\pm0.2$ \\ 
\hline
\end{tabular}}
\medskip
$^{{a}}$ IMF slope derived without radial correction;
$^{{b}}$~IMF slope derived with a radial correction for $r > 0.2$~pc to take into account the differential extinction (as proposed in SGB02, SBG05);
$^{{c}}$~this work. Individual derredening results described in~Sect.~4.1. \\
A~$2.5$~Myr theoretical isochrone with solar metallicity (Lejeune \& Shaerer \cite{lejeune}) was used to derive these results.
\end{table}