| Title:
             | 
Nil-clean and unit-regular elements in certain subrings of ${\mathbb M}_2(\mathbb Z)$ (English) | 
| Author:
             | 
Wu, Yansheng | 
| Author:
             | 
Tang, Gaohua | 
| Author:
             | 
Deng, Guixin | 
| Author:
             | 
Zhou, Yiqiang | 
| Language:
             | 
English | 
| Journal:
             | 
Czechoslovak Mathematical Journal | 
| ISSN:
             | 
0011-4642 (print) | 
| ISSN:
             | 
1572-9141 (online) | 
| Volume:
             | 
69 | 
| Issue:
             | 
1 | 
| Year:
             | 
2019 | 
| Pages:
             | 
197-205 | 
| Summary lang:
             | 
English | 
| . | 
| Category:
             | 
math | 
| . | 
| Summary:
             | 
An element in a ring is clean (or, unit-regular) if it is the sum (or, the product) of an idempotent and a unit, and is nil-clean if it is the sum of an idempotent and a nilpotent. Firstly, we show that Jacobson's lemma does not hold for nil-clean elements in a ring, answering a question posed by Koşan, Wang and Zhou (2016). Secondly, we present new counter-examples to Diesl's question whether a nil-clean element is clean in a ring. Lastly, we give new examples of unit-regular elements that are not clean in a ring. The rings under consideration in our examples are particular subrings of $\mathbb {M}_2(\mathbb {Z})$. (English) | 
| Keyword:
             | 
clean element | 
| Keyword:
             | 
nil-clean element | 
| Keyword:
             | 
unit-regular element | 
| Keyword:
             | 
Jacobson's lemma for nil-clean elements | 
| MSC:
             | 
11D09 | 
| MSC:
             | 
16S50 | 
| MSC:
             | 
16U60 | 
| idZBL:
             | 
Zbl 07088779 | 
| idMR:
             | 
MR3923584 | 
| DOI:
             | 
10.21136/CMJ.2018.0256-17 | 
| . | 
| Date available:
             | 
2019-03-08T15:00:02Z | 
| Last updated:
             | 
2021-04-05 | 
| Stable URL:
             | 
http://hdl.handle.net/10338.dmlcz/147627 | 
| . | 
| 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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| Reference:
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| . |