http://www.perlmonks.org?node_id=921097


in reply to Re: Another regex to solve ...
in thread Another regex to solve ...

    say unless m{(?<=([aeiou]))\1p\z};

That allows eg 'help' or slurp'.

Update: I've no idea why though, or why it also allows 'hops' and 'hoops'...

Update 2: Got it! It also of course allows 'rabbit', or any other string that doesn't end in 'p' preceded by whatever. It was the unless that momentarily confused me. :)