New York Journal of Mathematics
Volume 24 (2018), 848-855


Thomas Morgan

On the index of certain standard congruence subgroups

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Published: September 23, 2018
Keywords: automorphism groups, free groups, congruence subgroups
Subject: 20F28

For an epimorphism of the free group on two generators onto a finite group G, one can associate a finite index subgroup of the automorphism group of the free group called the standard congruence subgroup. We calculate the index of this group when G is a non-abelian semi-direct product of cyclic groups of prime order.


Author information

Thomas Morgan:
Department of Mathematics
The University of Oklahoma
Norman, OK 73019, USA.