When we talk about a regex
in the context of Perl, we don't mean Regular Expression
in the sense that a computer scientist would use (ie Typ-3 language of the Chomsky hierarchy), but rather "the thing that you but in m/...
These regexes are much more powerful than regular expressions, in fact they can do things that even Typ-2 langauges (context-free languages) can't. I've not yet seen a proof that they are Turing complete, so I don't know if they are.
Update: fixed Chomsky classification, thanks jakobi
- links to (nearly) everything that is Perl 6.