ISRAEL JOURNAL OF MATHEMATICS 163(1) 285-316 2008年1月 [査読有り]
We consider the harmonic measure on the Gromov boundary of a non-amenable hyperbolic group defined by a finite range random walk on the group, and study the corresponding orbit equivalence relation on the boundary. It is known to be always amenabl...
PROCEEDINGS OF THE AMERICAN MATHEMATICAL SOCIETY 134(6) 1771-1776 2006年 [査読有り]
We compute the exact value of Voiculescu's perturbation theoretic entropy of the boundary actions of free groups. This result is a partial answer of Voiculescu's question.
PACIFIC JOURNAL OF MATHEMATICS 223(1) 141-157 2006年1月 [査読有り]
Let Gamma be a Gromov hyperbolic group with a finite set A of generators. We prove that h(top)(Sigma(infinity)) <= k(infinity)(-1)(lambda(A)) <= gr(Gamma, A), where gr(Gamma, A) is the growth entropy, h(top)(Sigma(infinity)) is the Coornaert...
We construct a nuclear C*-algebra associated with the fundamental group of a graph of groups of finite type. It is well-known that every word-hyperbolic group with zero-dimensional boundary, in other words, every group acting trees with finite sta...
JOURNAL OF THE MATHEMATICAL SOCIETY OF JAPAN 56(1) 177-191 2004年1月 [査読有り]
We obtain the exact value of Voiculescu's invariant k(infinity)(-)(tau), which is an obstruction of the existence of quasicentral approximate units relative to the Macaev ideal in perturbation theory, for a tuple tau of operators in the following ...
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