#!/usr/bin/perl
use strict; use warnings; use Data::Dumper; 
my @a=(1,1,2,3,4,4,8,8);  
my @b=(3,4,3,5,6,7,9,10);
my $hoh={};

for ( 0 .. $#a){
    $hoh->{$a[$_]}->{$b[$_]}++;
    $hoh->{$b[$_]}->{$a[$_]}++;
}
sub recursive {
    my ($hoh, $key, $path, @vals) =@_;
    for ( grep { $_ ne $key } @vals){
        next if exists($path->{$_});
        $hoh->{$key}->{$_}++;
        $path->{$_}++;
        recursive($hoh, $key, $path, keys %{$hoh->{$_}} );
    }
}
for (sort {$a <=> $b}keys %$hoh){
    recursive($hoh, $_, {}, keys %{$hoh->{$_}} );   
}

#print Dumper $hoh;
for (sort {$a <=> $b}keys %$hoh){
    print "$_=" , join(",", keys %{$hoh->{$_}}), "\n";
}

__DATA__
this prints ...
1=6,4,3,7,2,5
2=6,4,1,3,7,5
3=6,4,1,7,2,5
4=6,1,3,7,2,5
5=6,1,4,3,7,2
6=1,4,3,7,2,5
7=6,1,4,3,2,5
8=10,9
9=8,10
10=8,9