Well, actually, the reference makes it exist. It's the hash assignment that delinks it. Witness the result of:

%last_name = ();
$x = \$last_name{fred}; # creates hash element, value is undef
$last_name{fred} = "flintstone";
print $$x; # prints flintstone
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So, your array-slice example would also work on a hash slice:

undef %last_name; @last_name{qw(fredref fred)} = (\$last_name{fred}, "
+flintstone");
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-- Randal L. Schwartz, Perl hacker