From: Hans Aberg (haberg@math.su.se)
Date: Tue Oct 09 2007 - 12:09:29 CDT
On 9 Oct 2007, at 17:06, Philippe Verdy wrote:
>>> So the question becomes really: What does a negated *regexp* match?
>>
>> The link I gave suggested: the complement language.
>
> Apparently you did not follow the discussions. This is just the
> intuitive
> answer, but not enough to determine the effective behaviour!
>
> The "complement" language can only be understood if you know what
> is the
> "complete" language, ...
In the link I gave, the vocabulary V is the character set.
> ...which is directly linked to the way texts are modelized
> and matched (including for special cases like aggregates: consider
> the case
> of "a*" or "a+", and think about what can be their complement,
> because it is
> exactly the same problem, if no semantic is defined for the "complete"
> language).
And in the link I gave, if you know the associated DFA, the
complement DFA can be constructed, which is then matches the
complement language in V*.
> You can't answer to these questions as it interacts with the possible
> (optional and unspecified) rules of the longest match or leftmost
> match if
> they are implemented, or with the ordering of matches when multiple
> matches
> are returned in a sequence or with enumerating methods like
> "regexp.nextMatch()" or "regexp.previousMatch()".
What is you point? - DFAs can be constructed for those.
Hans Åberg
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