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Vietnam Journal of Mathematics 34:3(2006) 265-273
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Simply Presented Inseparable $V(RG)$ Without $R$ Being Weakly Perfect or Countable
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Peter Danchev
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Abstract.
It is constructed a special commutative unitary ring $R$ of characteristic 2,
which is not necessarily weakly perfect (hence not perfect) or countable, and it is
selected a multiplicative abelian 2-group $G$ that is a direct sum of countable groups such that
$V(RG)$, the group of all normed 2-units in the group ring $RG$, is a direct sum of countable groups.
So, this is the first result of the present type, which prompts that the conditions for perfection or
countability on $R$ can be, probably, removed in general.
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2000 Mathematics Subject Classification: 16U60, 16S34, 20K10.
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Keywords: Unit groups, direct sums of countable groups, heightly-additive rings, weakly perfect rings.
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