Poisson-Pinsker factor and infinite measure preserving group actions
نویسندگان
چکیده
We solve the question of the existence of a Poisson-Pinsker factor for conservative ergodic infinite measure preserving action of a countable amenable group by proving the following dichotomy: either it has totally positive Poisson entropy (and is of zero type), or it possesses a Poisson-Pinsker factor. If G is abelian and the entropy positive, the spectrum is absolutely continuous (Lebesgue countable if G = Z) on the whole L-space in the first case and in the orthocomplement of the L-space of the Poisson-Pinsker factor in the second.
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