#! perl -slw
use strict;

my @ranges = map{
   my $a = rand( 900 );
   [ $a, $a + rand( 1000 - $a ) ]
} 1 .. 7;

print "$_ : [ @{ $ranges[ $_ ]} ]" for 0 .. 6;

my @overlaps;
for my $i1 ( 0 .. 6 ) {
    for my $i2 ( $i1+1 .. 6 ) {
        unless( $ranges[ $i1 ][ 0 ] > $ranges[ $i2 ][ 1 ]
             or $ranges[ $i1 ][ 1 ] < $ranges[ $i2 ][ 0 ]
        ) {
            push @{ $overlaps[ $i1 ] }, $i2;
        }
    }
}

defined $overlaps[ $_ ] 
    and print "$_ overlaps with @{ $overlaps[ $_ ] }" 
    for 0 .. 6;

__END__
c:\test>junk39
0 : [ 752.67333984375 781.958845257759 ]
1 : [ 45.5657958984375 108.800557162613 ]
2 : [ 574.887084960938 742.659308388829 ]
3 : [ 190.887451171875 585.887861438096 ]
4 : [ 20.7916259765625 200.777344871312 ]
5 : [ 306.353759765625 756.753877364099 ]
6 : [ 721.856689453125 821.619211696088 ]
0 overlaps with 5 6
1 overlaps with 4
2 overlaps with 3 5 6
3 overlaps with 4 5
5 overlaps with 6
[download]