[gecode-users] propagator - gist problem

Guido Tack tack at ps.uni-sb.de
Wed Nov 19 15:41:27 CET 2008

Alberto Delgado wrote:
> I'm  implementing a propagator and it works OK when i search for a  
> solution with Search  but when it comes to Gist an exception is  
> thrown:
> Space::clone: Attempt to invoke operation on failed space.
> This is what i do to modify the domain of the variable and check  
> whether the modification is valid:
>   ModEvent me =  x1.gq(home,constantValue);
>   if (me_failed(me)){
>    return ES_FAILED;
>    }
>   return ES_FIX;
> I can assure  that the propagator returns ES_FAILED (a std::cout  
> before the return ES_FAILED line) when it has to and doing some  
> extra tests i found out that if instead of modifying the domain of  
> x1 i just check whether the variable's domain is empty  the  
> exception disappears.

Are you sure that your propagator computes a fixed point?  If not, try  
returning ES_NOFIX and see if the problem goes away.


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