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Hyperlinearity, essentially free actions and L2-invariants. The sofic property

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We prove that Connes’ Embedding Conjecture holds for the von Neumann algebras of sofic groups, that is sofic groups are hyperlinear. Hence we provide some new examples of hyperlinearity. We also show that the Determinant Conjecture holds for sofic groups as well. We introduce the notion of essentially free actions and amenable actions and study their properties.

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References

  1. Bedos, E., de la Harpe, P.: Moyennabilité intérieure des groupes: définitions et exemples. Enseign. Math. (2) 32, 139–157 (1986)

    Google Scholar 

  2. Brenner, J.L.: Covering theorems for FINASIGs. VIII. Almost all conjugacy classes in A n have exponent ≤ 4. J. Austral. Math. Soc. Ser. A. 25, 210–214 (1978)

  3. Champetier, C.: L’espace des groupes de type fini. Topology 39, 657–680 (2000)

    Article  Google Scholar 

  4. Clair, B.: Residual amenability and the approximation of L2-invariants. Michigan Math. J. 46, 331–346 (1999)

    Article  Google Scholar 

  5. Deuber, W.A., Simonovits, M., Sós, V.T.: A note on paradoxical metric spaces. Studia Sci. Hung. Math. 30, 17–23 (1995)

    Google Scholar 

  6. Elek, G., Szabó, E.: On sofic groups, to appear in the Journal of Group Theory (http://arXiv.org/abs/math/0305352).

  7. Elek, G., Szabó, E.: Sofic groups and direct finiteness. Journal of Algebra 280, 426–434 (2004)

    Article  Google Scholar 

  8. Gromov, M.: Endomorphisms of symbolic algebraic varieties. J. Eur. Math. Soc. 1, 109–197 (1999)

    Google Scholar 

  9. Hall, J.I.: Locally finite simple groups of finitary linear transformations. Finite and locally finite groups NATO Adv. Sci. Inst. Ser. C. Math. Phys 471, 147–188

  10. Kirchberg, E.: On nonsemisplit extensions, tensor products and exactness of group C-algebras. Invent. Math. 112, 449–489 (1993)

    Article  Google Scholar 

  11. Lück, W.: Approximating L2-invariants by their finite-dimensional analogues. Geom. Funct. Analysis 4, 455–481 (1994)

    Google Scholar 

  12. Lück, W.: L2-invariants: theory and applications to geometry and K-theory. Ergebnisse der Mathematik und ihrer Grenzgebiete. 3. 44, Springer, Berlin Heidelberg (2002)

  13. Ozawa, N.: About the QWEP conjecture. International Journal of Math. 15, 501–530 (2004)

    Article  Google Scholar 

  14. Paterson, A.L.T.: Amenability. Mathematical Surveys and Monographs 29 American Mathematical Society, Providence (1988)

  15. Radulescu, F.: The von Neumann algebra of the non-residually finite Baumslag group < a,b | a b3 a-1 = b2 > embeds into Rω, preprint 2002 (http://www.arxiv.org/abs/math.OA/0004172).

  16. Schick, T.: L2-determinant class and approximation of L2-Betti numbers. Trans. Amer. Math. Soc. 353, 3247–3265 (2001)

    Article  Google Scholar 

  17. Schick, T.: Integrality of L2-Betti numbers. Math. Ann. 317, 727–750 (2000)

    Google Scholar 

  18. Vershik, A.M., Gordon, E.I.: Groups that are locally embeddable in the class of finite groups. Algebra i Analiz 9, 71–97 (1997)

    Google Scholar 

  19. Weiss, B.: Sofic groups and dynamical systems, (Ergodic theory and harmonic analysis, Mumbai, 1999) Sankhya Ser. A. 62, 350–359 (2000)

    Google Scholar 

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Correspondence to Gábor Elek.

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Mathematics Subject Classification (2000): 43A07, 55N25

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Elek, G., Szabó, E. Hyperlinearity, essentially free actions and L2-invariants. The sofic property. Math. Ann. 332, 421–441 (2005). https://doi.org/10.1007/s00208-005-0640-8

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  • DOI: https://doi.org/10.1007/s00208-005-0640-8

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