Hi,

you're right that you'd have to implement your own propagator for that.  Before 
you do that you should check if you actually need full reification (i.e. b <-> 
c) or if an implication would be enough (b -> c).  In the latter case, you 
don't need to implement the negation of c (where c is your extensional 
constraint).

If you implement the full version, negating a DFA is (in principle) easy, just 
make all accepting states rejecting and all rejecting states accepting.  In the 
Gecode representation the rejecting states aren't represented directly so 
you'll have to work around that a bit.

Cheers,
Guido

-- 
Guido Tack
http://www.csse.monash.edu/~guidot/



On 14 Jun 2014, at 8:35 pm, Amina Kemmar <kemmar.am...@gmail.com> wrote:

> Hi all,
> 
> I want to use a reification version of the extensional constraint, but I 
> think that it is not implemented in Gecode.
> The chapter 24 explains how to implement a reification version of a 
> constraint, I understand that we need the negation of the automata DFA. So, I 
> want to know if there is an easy way to do this with extensional constraint? 
> If you have any details about this, it will be very helpful for me.
> 
> Thanks.
> 
> Best regards,
> ---
> Amina
> 
> _______________________________________________
> Gecode users mailing list
> users@gecode.org
> https://www.gecode.org/mailman/listinfo/gecode-users

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