[gecode-users] Gecode/J New users

[Guido Tack]

Malcolm Ryan wrote:

> Hi, I'm looking around at different Java CSP packages to find one in
> which I can work on a problem I have. Gecode/J looks nice, but
> documentation is thin. Can you please answer a few of my questions?
>
> 1) You include finite domain set variables, which I need. What
> operations are available on them?

You find the propagators that are available in the current version here:
http://www.gecode.org/gecodej/doc/group__TaskIntSet.html

Maybe that's not exactly what you were looking for - what kind of  
operations do you mean?

> 2) Can you reify constraints as boolean variables?

Yes, many constraints can be reified.  E.g., have a look at
http://www.gecode.org/gecodej/doc/group__TaskIntIntEq.html
The reified versions mention something like "<=> b" in the  
documentation, where b is a BoolVar.

> 3) Do you have any means to label constraints with meaningful tags
> for debugging?

No, that's currently not possible.  What kind of information would  
you like to attach to a constraint? We are currently integrating  
reflection capabilities into the C++ base library, which might  
eventually also become available in Java.

> 4) Can I implement new constraints in Java? If so, how?

Yes, that's possible.  Have a look at the QueensJavaPropagator.java  
example file distributed with Gecode/J.  However, the interface for  
implementing propagators is pretty heavy-weight and not very  
efficient.  We currently don't encourage users to implement  
propagators that are critical for efficiency in Java, but rather to  
implement them in C++ and then interface to Java.

> and I guess the most important question:
>
> 5) Is this project actively used and supported?

Yes, it is.  It hasn't seen an update in quite a while because we are  
busy preparing the next major version (2.0.0), which should be  
available within the next month.  We are actively using it mainly for  
teaching CP courses, here at Saarland University and at KTH, and some  
other universities.

Cheers,
	Guido