On two open problems about strongly clean rings
2004 ◽
Vol 70
(2)
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pp. 279-282
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Keyword(s):
A ring is called strongly clean if every element is the sum of an idempotent and a unit which commute. In 1999 Nicholson asked whether every semiperfect ring is strongly clean and whether the matrix ring of a strongly clean ring is strongly clean. In this paper, we prove that if R = {m/n ∈ ℚ: n is odd}, then M2(R) is a semiperfect ring but not strongly clean. Thus, we give negative answers to both questions. It is also proved that every upper triangular matrix ring over the ring R is strongly clean.
2019 ◽
Vol 19
(03)
◽
pp. 2050053
2016 ◽
Vol 15
(07)
◽
pp. 1650121
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2009 ◽
Vol 51
(3)
◽
pp. 425-440
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Keyword(s):
2019 ◽
Vol 18
(05)
◽
pp. 1950096
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