my $x ='((A & B)\' | (A & C & (A & B & D | (A & (B\' & D)\')\'))';

##</code><code>##

(!(A & B) | (A & C & (A & B & D | !(A & !(!B & D))))

##</code><code>##

#!/usr/bin/perl
use strict;
use warnings;
my $x = '((A & B)\' | (A & C & (A & B & D | (A & (B\' & D)\')\'))'; 

print "Given: $x\n"; 

$x =~ s/(\(\s*[^()]+\s*\))\'/\!$1/g; 

print "Calculated: ",$x,"\n"; $x =~s/([a-zA-Z]\w*)\'/\!$1/g; 

$x =~ s/((\(){1}\s*.*?([!][(])+.*?\)\s*)\'/\!$1/g;

print "NewVl : ",$x,"\n";