# Question in the analysis

• Nov 28th 2012, 11:41 PM
soso123
Question in the analysis
• Nov 29th 2012, 04:27 AM
girdav
Re: Question in the analysis
Consider the linear map \$\displaystyle L_k\colon x\mapsto x_{2k}\$. Then \$\displaystyle Y=\bigcap_{k\geqslant 1}\ker L_k\$. To conclude, show that \$\displaystyle L_k\$ is linear and bounded.
• Nov 29th 2012, 05:38 AM
soso123
Re: Question in the analysis
Thanks
• Nov 29th 2012, 05:39 AM
girdav
Re: Question in the analysis
What don't you understand exactly?
• Nov 29th 2012, 06:10 AM
soso123
Re: Question in the analysis
I want to prove that a group be closed
• Nov 29th 2012, 06:24 AM
girdav
Re: Question in the analysis
What do you mean? Where do you see a group?
• Nov 29th 2012, 07:33 AM
HallsofIvy
Re: Question in the analysis
Are you sure this course work is from a class you are taking? You seem to be saying that you do not know what any of this means. For example, do you know what "\$\displaystyle l^1\$" means? How is the topology defined on that set ("group" is, mathematically, the wrong word)? How is "closed" defined in that topology?