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Timeline for Sigma-algebras on Banach Spaces.

Current License: CC BY-SA 2.5

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Apr 13, 2017 at 12:58 history edited CommunityBot
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Mar 22, 2011 at 13:56 comment added Ravil Mudarisov Thanks a lot. About l∞ we should use open ball of radius 1, and i think to show that it is neither cylindrical set nor can not be represented as intersection of cylinders.
Mar 22, 2011 at 13:39 comment added Gerald Edgar Set $[0,1/2]^{[0,1]}$ does not depend on only countably many coordinates, so it is not Baire. These are comments rather than answers, since they are not about $l^\infty$.
Mar 22, 2011 at 8:15 history edited Ravil Mudarisov CC BY-SA 2.5
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Mar 22, 2011 at 5:07 comment added Ravil Mudarisov But why [0,1/2]^{[0,1]} is not baire? And what about l-infinitive?
Mar 21, 2011 at 23:54 comment added Gerald Edgar Correct, a singleton is a closed set, therefore Borel. Also, the more complicated set $[0,1/2]^{[0,1]}$ is closed, therefore Borel.
Mar 21, 2011 at 20:07 comment added Ravil Mudarisov And i think of the set {0}.
Mar 21, 2011 at 19:55 comment added Ravil Mudarisov "The product sigma-algebra has the property that every set in it depends on only countably many coordinates." - that is from defenition of Baire sigma-algebra on product spaces, am I right?
Mar 21, 2011 at 19:42 comment added Ravil Mudarisov Ok, they are not equal. It would be great if there is example of Borel, not Baire(Cylindrical) set. I think of [0,1/2]^{[0,1]}, but didnt prove it yet. Maybe you can give me other examples?
Mar 21, 2011 at 18:29 comment added Gerald Edgar And $[0,1]^{[0,1]}$ is interesting for the sigma-algebra, too. The product sigma-algebra (= the Baire sigma-algebra) has the property that every set in it depends on only countably many coordinates. In particular, a singleton is NOT in this sigma-algebra. So the Baire sigma-algebra is not the same as the Borel sigma-algebra.
Mar 21, 2011 at 17:00 comment added Nate Eldredge $[0,1]^{[0,1]}$ (with the product topology) is not metrizable.
Mar 21, 2011 at 16:31 history edited Ravil Mudarisov
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Mar 21, 2011 at 16:07 history asked Ravil Mudarisov CC BY-SA 2.5