Nice and short :)

But I'm uncertain it works as I intend. For example, try these names:

__DATA__
Adam Harper
Alan Harper
[download]

With your code I get this:

d:\tmp>test.pl
$VAR1 = {
          'A H' => undef,
          'A Ha' => undef
        };
[download]

Both of these are ambiguous.

EdwardG,
You are right - I only had a minimal chance to test it. I think it works to your satisfacation. Sorry it took a while to get back to you - stupid thing called work ;-)

#!/usr/bin/perl
use strict;
use warnings;

my %name = map {chomp; $_ => undef} <DATA>;

my $num_names = 0;
for my $person ( keys %name ) {
    my @names = split " " , $person;
    $num_names = @names if @names > $num_names;
    $_ = ucfirst lc $_ for @names;
    $name{ $person } = \@names;
}
my $finished = 0;

my $index = 0;
while ( ! $finished ) {
    my $update = 0;
    for my $person ( keys %name ) {
        next if ! $name{$person}[$index];
        if ( $name{$person}[$index] =~ /(\w+)\w/ ) {
            my $new_name = $1;
            if ( ! grep { $new_name eq $_ }
                map { $name{$_}[$index] }
                grep { @{$name{$_}} == @{$name{$person}} } keys %name
               ) {
                    $update = 1;
                    $name{$person}[$index] = $new_name;
            }
        }
    }
    $index++ if ! $update;
    $finished = 1 if $index > $num_names;
}
print "$_ => @{ $name{$_} }\n" for keys %name;
[download]

Cheers - L~R

Alan Harper => A H     <-- AMBIGUOUS!
Adam Harper => Ad Ha
[download]

The requirement is that all derived 'initials' should be unambiguous in which name they refer to.

'A H' could refer to Alan or Adam.

My code does this:

Adam Harper => AdHa
Alan Harper => AlHa
[download]