Another exercise involves fixing the number of nodes to the maximum number
and then moving the nodes so that they are positioned in the optimal
locations (the so-called * r* method or relocation method). Still
another possibility is to use an de-refinement strategy, in which regions
of the discretized domain that were too finely meshed in the original mesh
can be ``unrefined'' and help balance the total number of degrees of
freedom. At some point, however, for most large three-dimensional
problems, one must face the option of parallelizing the algorithms so
that they can be run on either a distributed system of high-end
workstations or a massively parallel machine. The use of such techniques
for adaptive mesh generation is just in its infancy, but is certainly a
topic of considerable importance to researchers who work on large-scale
finite element systems.

*To find out more about parallel adaptive refinement methods and adaptive
methods in general,
see [45,34,39,40,42]. *