sub find_symmetry
  {
  my $compound = shift @_;
  $$compound{Symmetries} = [];
  my $M_matrix = $$compound{Mapping};
  my $A_matrix = $$compound{Adjacency};
  my @isomorphs;
  my $row = 0;
  my $dimension = $#$A_matrix;
  my @indices = (0..$dimension);
  my @reverse = reverse @indices;
  my @used = map {0;} (@indices);
  my @mapping = map {-1;} (@indices);
  my (@sm_rows, @same_rows);
  foreach my $row (@$A_matrix) { push @sm_rows, $row; }
  foreach my $row (@$M_matrix) { push @same_rows, $row;}
  my $equate_sub = sub 
    {
    for (reverse(0..$row))
      {
      my (@smrow, @omrow);
      alias @smrow = @{$sm_rows[$_]};
      alias @omrow = @{$sm_rows[$mapping[$_]]};
      for (0..$row)
        {
        if ($smrow[$_] != $omrow[$mapping[$_]])
          {
          return 0;
          }
        }
      }
    return 1;
    };

  LOOP: while(1)
    {
    do { $mapping[$row] ++ } while ( $mapping[$row] <= $dimension and ($used[$mapping[$row]] == 1 || $same_rows[$row][$mapping[$row]] == 0 ));
    next if ($mapping[$row] > $dimension);
    if ( $row == $dimension )
      {
      OUTER:
        {
        for (@indices)
          {
          my (@smrow2, @omrow2);

          alias @smrow2 = @{$sm_rows[$_]};
          alias @omrow2 = @{$sm_rows[$mapping[$_]]};
          for (@reverse)
            {
            if ( $smrow2[$_] != $omrow2[$mapping[$_]] )
              {
              last OUTER;
              }
            }
          }
        push @{$$compound{Symmetries}}, [@mapping];
#        print join(",",@mapping), "\n";
        }
      }
    elsif ( $row == 0 or &$equate_sub == 1 )
      {
      $used[$mapping[$row]] = 1;
      $row++;
      }
    }
  continue
    {
    while ( $row >= 0 and $mapping[$row] >= $dimension )
      {
      last LOOP if ($row == 0);
      $mapping[$row] = -1;
      $row --;
      $used[$mapping[$row]] = 0;
      }
    }
  $$compound{Mapping} = undef;
  $$compound{Adjacency} = undef;
#  return \@isomorphs;
  }