ger group handles. Their value (say, "group
= 10") might be the same but the actual content different in different
subsets of processors!!!  If two subsets assign the same number to the
group handle, each subset will treat the group as "its own", so
'proc<sub>in</sub><sub>set'</sub> below will be true.  The only reliable way to test
membership of the current process in a group is then to explicitly use
the list of group ranks in the base group.  Or to include in the
'dist' structure a field saying "I belong