@inproceedings{Bac:Wil:WS-CP98,
author = {Backofen, Rolf and Will, Sebastian},
title = {Excluding Symmetries in Concurrent Constraint
         Programming},
booktitle = {Workshop on Modeling and Computing with Concurrent
             Constraint Programming},
year = {1998},
doi = {https://www.semanticscholar.org/paper/Excluding-Symmetries-in-Concurrent-Constraint-Backofen-Will/542ba33068f962839b027b9442638bd070727783},
user = {will},
abstract = {
            In many problems, non-determinism naturally arises in an concurrent
            constraint-based formulation in form of disjunctive constraints. To
            check consistency of disjunctive constraints, one needs to perform
            search by splitting the constraint store into local computation
            stores.  An important problem there is to eliminate symmetries, which
            give rise to many different but ''similar'' solutions found by the
            search procedure.  Since symmetries will give rise to an (often
            exponential) amplification of the search space, symmetry exclusion
            promises to efficiently prune the search tree.
            
            Hence, many constraint programmers have constructed mechanisms to
            exclude at least some of the symmetries of their
            problem. Unfortunately, symmetry exclusion was often not
            straightforward to implement and had to be redesigned for every
            special problem or enumeration strategy, which leaded to an
            inflexibility in the program structure once it was introduced. Often
            symmetry exclusion was not done at all or only for a small set of
            symmetries. In other cases, where symmetry exclusion was implemented
            it distracted the programmers attention from more important tasks.
            
            The contribution of our work is to give a generally applicable method
            for the exclusion of arbitrary symmetries. To our knowledge, this is
            the first general and declarative method for excluding symmetries in
            concurrent constraint programming.}
}