function dumpParticipants(Graph $g)
{
    $nids = $g->getNodeIds();
    $parts = array();
    foreach ($nids as $id) {
        $p = $g->getParticipants(array($id));
        asort($p);
        $key = join(',', $p);
        $parts[$key] = "Participating group: {$key}";
    }
    echo "\n" . join("\n", $parts);
    // All
    $p = $g->getParticipants();
    asort($p);
    $key = join(',', $p);
    echo "\nParticipants ALL   : {$key}";
}