#!/usr/bin/perl -w
use strict;
use Data::Dumper;

my %a; 

{
   no autovivification 'exists';
   
   if (exists ( $a{'abd'}->[0] ) )
   { print "yes \n"; } 
   
}

print Dumper \%a; 

if (exists ( $a{'abd'}->[0] ) )
   { print "yes \n"; } 
   
print Dumper \%a;

__END__
$VAR1 = {};
$VAR1 = {
          'abd' => []
        };