#use strict;
use warnings;

my %A = (horse=> 'a',lion=>'b' ,mule=>'c',tiger =>'d');
my @order= sort  keys %A;

while (<DATA>) {
  warn("Line $.: cannot understand: $_") , next unless /(\w+);(\w+)/;
  my ($row, $col) = ($1,$2);
 $A {$row}{$col}++;
  $A{$col}{$row}++;
}

# print col. header
print "    ";
printf(" %2s",$_) for (@order);
print "\n";

#print matrix A
for my $row (@order) {
  printf(" %2s", $row);

  for my $col (@order) {
    printf(" %3d",  exists $A{$row}{$col} ? "1" : "0" );
  }
  print "\n";
}


__DATA__
horse;tiger
lion;mule
lion;tiger
horse;mule

##</code><code>##

I have got ouput 
        horse lion mule tiger
 horse   0   0   1   1
 lion   0   0   1   1
 mule   1   1   0   0
 tiger   1   1   0   0