effects of the mass segregation and from the LFs of Figure \[M55fdl\]. Figure \[M55mf\] clearly shows that the MF starting from the center out to the outer envelope of the cluster is flat: the index $x$ of the power law, $\xi=\xi_0m^{-(1+x)}$, best fitting the data are: $x=-2.1\pm0.4$, $x=-0.8\pm0.3$, and $x=0.7\pm0.4$ going from the inner to the outer anulii; this means that the slope of the global MF (of all the stars in M55) should be extremely flat. Indeed, the slope of the global mass function obtained from the corresponding LF of all the stars of M55 is: $x=-1.0\pm0.4$ This result agrees with the results of [@Irwin84], while the results of [@Pryor91] appear in contrast to what we have found here.

Our MF in the outer radial bin can be compared with the high-mass MF of [@Mand96], obtained from a field located at $\simeq6$ arcmin from the center of M55. As already reported in Section 2, [@Mand96] obtained a deep MF for M55 (down to $M\simeq0.1\Msun$) which they describe with two power laws connected at $M\simeq 0.4\div0.5\Msun$. Their value of $x=0.5\pm0.2$ for the high-mass end of the mass function ($0.5<M/\Msun<0.8$) is in good agreement with our value of $x=0.7\pm0.4$, obtained in 