Ian Miguel, University of St Andrews, UK
One way of improving usability is by extending CP technology to enable models to be formulated at a higher level of abstraction. For instance, support for set variables (variables whose domain values are sets) in many constraint languages and solvers has abstracted away from the low-level details of how the set variable is represented; the user no longer needs to know these details. However, variables that take certain other types of values, such as functions and relations, are not yet supported directly by constraint solvers. In this case, the abstract variable can be refined into a representation that comprises a set of more primitive variables and a collection of constraints among them. In order to avoid forcing the user to perform this step manually, automated refinement is a key goal.
Automation can also aid the modelling process by transforming a constraint model into one that can be solved more effectively. Such transformations include adding implied constraints, adding symmetry-breaking constraints, adding constraints to exploit dominances in optimisation problems, removing propagation-redundant constraints and creating relaxed versions of the initial problem.
This special issue is devoted to the development and use of abstraction and automation facilities in constraint modelling. We invite submissions from interested authors in this challenging and important area.
When submitting, please use the subject "Constraints Special Issue Paper Submission" and clearly specify the e-mail address and phone number of the corresponding author. Receipt of papers will be acknowledged. Submissions will be reviewed by at least two reviewers. All accepted papers will meet the usual high-quality standards of the Constraints Journal.
Authors intending to submit should send an expression of interest (including a provisional title, list of authors and a few sentences outlining the topic of the paper) to ianm@cs.st-and.ac.uk by May 1st, 2007.