Algorithms for Finite Group Epimorphism Testing
Abstract
The Group Epimorphism Problem (GpEpi) asks, given two finite groups G1 and G2, whether there exists a surjective group homomorphism, or epimorphism, from G1 to G2. When the input groups are given by their multiplication (Cayley) tables, the problem admits a quasipolynomial-time algorithm in general, but little is known about its complexity for structured classes of finite groups. In this paper, we study the computational complexity of GpEpi for several well-studied classes of finite groups. Our main results are polynomial-time epimorphism tests for several classes of groups for which polynomial-time isomorphism testing was previously known: Groups with Abelian normal Hall subgroups with cyclic complement; Groups with (product of) elementary Abelian normal Hall subgroup with elementary Abelian complement; and Groups with some constraints on their Abelian chief factors.
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BibTeX
@misc{grochow2026algorithms,
title = {{Algorithms for Finite Group Epimorphism Testing}},
author = {Joshua A. Grochow and Pranjal Srivastava and Dhara Thakkar},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.07429},
eprint = {2609.07429},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.07429},
}
RIS
TY - UNPB
TI - Algorithms for Finite Group Epimorphism Testing
AU - Joshua A. Grochow
AU - Pranjal Srivastava
AU - Dhara Thakkar
PY - 2026
DA - 2026/09/07
PB - arXiv
DO - 10.48550/arxiv.2609.07429
UR - https://arxiv.org/abs/2609.07429
AB - The Group Epimorphism Problem (GpEpi) asks, given two finite groups G_1 and G_2, whether there exists a surjective group homomorphism, or epimorphism, from G_1 to G_2. When the input groups are given by their multiplication (Cayley) tables, the problem admits a quasipolynomial-time algorithm in general, but little is known about its complexity for structured classes of finite groups. In this paper, we study the computational complexity of GpEpi for several well-studied classes of finite groups. Our main results are polynomial-time epimorphism tests for several classes of groups for which polynomial-time isomorphism testing was previously known: Groups with Abelian normal Hall subgroups with cyclic complement; Groups with (product of) elementary Abelian normal Hall subgroup with elementary Abelian complement; and Groups with some constraints on their Abelian chief factors.
ER -