Every -Algebra is Normal
Abstract: Using set-theoretic methods, we prove that every -algebra is normal, resolving a question of Wright that has stood open for 46 years. This was previously known in the case of -factors, by work of Saitô and Wright. We also show that if there is a model of with an -algebra that fails to be monotone complete, then in some forcing extension of there is an -factor that fails to be monotone complete, implying that any proof that all -factors are monotone complete yields a proof that all -algebras are monotone complete. Both results build on transfer principles for Boolean-valued factor representations originally developed by Ozawa. This work was assisted by the Danus LLM orchestration system.
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