A copy of this work was available on the public web and has been preserved in the Wayback Machine. The capture dates from 2018; you can also visit the original URL.
The file type is application/pdf.
Counting subgroups of non-euclidean crystallographic groups
1999
Mathematica Scandinavica
Preserved Fulltext
A method is obtained for counting the normal subgroups N of a noneuclidean crystallographic group À without reflections, with a given finite quotient group ÀaN; this has applications to the enumeration of regular coverings of orbifolds. The method, which involves Mo« bius inversion and character theory, is also applied to count normal surface subgroups and non-normal subgroups of finite index in À .
doi:10.7146/math.scand.a-13930
fatcat:myp4wyhbrbazbbvwkbdri4khcy