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From: Zdislav V. Kovarik on 27 Jan 2010 15:20


On Mon, 25 Jan 2010, Legendre wrote:

> I want to find a set which is algebra but not sigma-algebra.
>
> Thanks

On the real line, try the algebra A generated by all intervals
of the type [a,b). Can you find the interval (0,1) in it?
(It is in the sigma-algebra generated by A.)
(And you can do the proving yourself.)

(Or: in the positive integers, the algebra generated by finite subsets...)

Cheers,
ZVK(Slavek).
From: Legendre on 28 Jan 2010 08:32
Thank you very much. I got the idea.
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