[gecode-users] Singleton Arc Consistency Preprocessing

[Tyrel Russell]

Hi,

Is there a preferred method for applying singleton arc consistency 
preprocessing in Gecode?

The idea that I was considering was to fix each variable value pair and 
determine if a nogood is generated by applying arc consistency with the 
variable-value fixed.  If so, add this nogood to a set of stored nogoods 
and enforce the new set of constraints, iterate through this process 
until no further nogoods are found.

There seem to be two problems with this approach.  First, it seems to be 
necessary to only add constraints in the constructor of a Space object 
or during search which means generating a specific constructor for this 
purpose.  Is there a better way to add constraints to a Space object on 
the fly?  Second, there is an issue of efficiency.  There would a large 
number of calls to my hypothetical constructor which may not be efficient.

I know that singleton arc consistency preprocessing was removed from 
Gecode several versions ago.  Was this because it was too expensive to 
be effective?

Thanks,

Tyrel Russell