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International Journal of Mathematics and Mathematical Sciences - Volume 31 2002, Issue 8, Pages 509-512

Department of Mathematics, University of Zanjan, Zanjan, Iran

Received 2 August 2001

Copyright © 2002 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Let R be a ring, and denote by R,R the group generated additively by the additive commutators of R. When Rn=MnR the ring of n×n matrices over R, it is shown that Rn,Rn is the kernel of the regular trace function moduloR,R. Then considering R as a simple left Artinian F-central algebra which is algebraic over F with Char F=0, it is shown that R can decompose over R,R, as R=Fx+R,R, for a fixed element x∈R. The space R-R,R over F is known as the Whitehead space of R. When R is a semisimple central F-algebra, the dimension of its Whitehead space revealsthe number of simple components of R. More precisely, we show that when R is algebraic over F and Char F=0, then the number of simple components of R is greater than or equal to dimF  R-R,R, and when R is finite dimensional over F or is locally finite over F in the case of Char F=0, then the number of simple components of R is equal to dimF  R-R,R.

Autor: M. Arian-Nejad



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