Hi,

If extraction of contents in inthe inner paranthesis is your only concern, try

$str = "((A AND B) OR (C AND D) NOT E)";
print "$1\n" while( $str =~ /\(([\w\s]+)\)/g);
[download]

this may not be the best solution, but this is the first solution I have.

Cheers !

--VC

There are three sides to any argument.....
your side, my side and the right side.