From: Hans Aberg (haberg@math.su.se)
Date: Sat Oct 13 2007 - 12:06:24 CDT
On 13 Oct 2007, at 17:38, Philippe Verdy wrote:
>>> Andy and I put together a paper of recommendations for the UTC at
>>> http://docs.google.com/Doc?id=dfqr8rd5_32kv97tx .
>>
>> I suspect you will run into problems when mixing complement with the
>> Kleene closure (zero or more concatenations) operator (and other
>> operators generating an infinite number of strings in the associated
>> language).
>>
>> So one safe way is to admit the usual set operations on character
>> classes only, and letting regular expressions having only the usual
>> operators acting on character classes.
>
> This is only true if you use the assumption that the current state
> of the
> generated DFA should be represented using a single integer type.
I am not sure what the DFAs have here to do.
If the RE r generates the language L(r), and ~r is the complement,
what is the definition of L(~r)? Specifically:
If L(ε) is the empty string, what is L(~ε)?
What is the definition of L(~(r*))?
Hans Åberg
This archive was generated by hypermail 2.1.5 : Sat Oct 13 2007 - 12:08:23 CDT