| Title:
             | 
On decomposability of finite groups (English) | 
| Author:
             | 
Chen, Ruifang | 
| Author:
             | 
Zhao, Xianhe | 
| Language:
             | 
English | 
| Journal:
             | 
Czechoslovak Mathematical Journal | 
| ISSN:
             | 
0011-4642 (print) | 
| ISSN:
             | 
1572-9141 (online) | 
| Volume:
             | 
67 | 
| Issue:
             | 
3 | 
| Year:
             | 
2017 | 
| Pages:
             | 
827-837 | 
| Summary lang:
             | 
English | 
| . | 
| Category:
             | 
math | 
| . | 
| Summary:
             | 
Let $G$ be a finite group. A normal subgroup $N$ of $G$ is a union of several $G$-conjugacy classes, and it is called $n$-decomposable in $G$ if it is a union of $n$ distinct $G$-conjugacy classes. In this paper, we first classify finite non-perfect groups satisfying the condition that the numbers of conjugacy classes contained in its non-trivial normal subgroups are two consecutive positive integers, and we later prove that there is no non-perfect group such that the numbers of conjugacy classes contained in its non-trivial normal subgroups are 2, 3, 4 and 5. (English) | 
| Keyword:
             | 
non-perfect group | 
| Keyword:
             | 
$G$-conjugacy class | 
| Keyword:
             | 
$n$-decomposable group | 
| MSC:
             | 
20D10 | 
| MSC:
             | 
20E45 | 
| idZBL:
             | 
Zbl 06770134 | 
| idMR:
             | 
MR3697920 | 
| DOI:
             | 
10.21136/CMJ.2017.0197-16 | 
| . | 
| Date available:
             | 
2017-09-01T12:27:17Z | 
| Last updated:
             | 
2020-07-03 | 
| Stable URL:
             | 
http://hdl.handle.net/10338.dmlcz/146863 | 
| . | 
| Reference:
             | 
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| Reference:
             | 
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| Reference:
             | 
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| Reference:
             | 
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| Reference:
             | 
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| Reference:
             | 
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| Reference:
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| Reference:
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| Reference:
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| . |