The GAP 4 package CrystCat provides a catalog of crystallographic groups
of dimensions 2, 3, and 4 which covers most of the data contained in the
book "Crystallographic groups of four-dimensional space" by H. Brown, R.
Bülow, J. Neubüser, H. Wondratschek, and H. Zassenhaus (John Wiley, New
York, 1978). This catalog was previously available in the library of
GAP 3. The present version for GAP 4 has been moved into a separate
package, because it requires the package Cryst, which is loaded
automatically by CrystCat. The benefit of this is that space groups
extracted from the catalog now have the rich set of methods provided by
Cryst at their disposal, and are no longer dumb lists of generators.
Moreover, space groups are now fully supported in both the
representation acting from the left and the representation acting from
the right.
