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9:24 AM
I'm not sure whether to put this doubt into a question on the main site, or whether there's a chatroom for it... My doubt is «Is there a sequence in R, for which either limsup or liminf are not defined?»
 
 
4 hours later…
1:07 PM
@Anoldmaninthesea. I think that the Calculus and analysis room would be fine.
In any case, as far as I can tell there is no such sequence. (Assuming you allow values to be $\pm\infty$.)
One of several equivalent definitions of limit superior is $\limsup x_n = \lim_{n\to\infty} \sup_{k\ge n} x_k$.
We know that limit of a monotone sequence of (extended) real numbers exists (if we allow infinite values).
The sequence $\sup_{k\ge n} x_k$ is monotone.
 
1:43 PM
Many thanks Martin ;)
 
 
2 hours later…
4:01 PM
0
Q: about isometry classes

Ninja hatori This is Theorem 2.3.8 from Scharlau's book Quadratic and Hermitian Forms I know that $\mathbb{F}_q$/$\mathbb{F}_q^2$ has index 2 so it has only two elements ; since 1 is also square in $\mathbb{F}_q$ why it is one of element of $\mathbb{F}_q$/$\mathbb{F}_q^2$. Also what is meaning form $\langl...

 

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