Torsion Theories for Algebras of Affiliated Operators of Finite Von Neumann Algebras

Lia Vaš
2007 Rocky Mountain Journal of Mathematics  
The dimension of any module over an algebra of affiliated operators U of a finite von Neumann algebra A is defined using a trace on A. All zero-dimensional U -modules constitute the torsion class of torsion theory (T, P). We show that every finitely generated U -module splits as the direct sum of torsion and torsion-free part. Moreover, we prove that the theory (T, P) coincides with the theory of bounded and unbounded modules and also with the Lambek and Goldie torsion theories. Lastly, we use
more » ... es. Lastly, we use the introduced torsion theories to give the necessary and sufficient conditions for U to be semisimple. 2000 Mathematics Subject Classification. 16W99, 46L99, 16S90.
doi:10.1216/rmjm/1199649837 fatcat:kavt7dxmtrg55p5gxauawpph24