Possible Duplicate:
  Complex Lie group without faithful real representations?  


We know that for a matrix (linear) Lie group $G$, we define it to be a closed subgroup of $GL(n,\mathbb{C})$. But Lie groups are defined as manifolds in $\mathbb{R}^n$   for some $n$, in general. The question is that, do we know any Lie group which is not a matrix Lie group? Thank you very much.


Question: Photo icons have generic picture only
Answer: I had this problem with my new installation of Windows 8.1.

After I had installed most of the regular Windows applications I was using in Windows 7, I started on a getting-acquainted tour of the new OS and its "ModernUI"apps.

The generic file type icons displayed in the Photos app really puzzled me, but a lot of Internet searching finally led to the solution: any installation of a recent version of the open source office suite "LibreOffice" changes the Windows registry of common graphics file types in an undesirable way, so that they are treated as a document rather than a picture.

There is a very long thread about the problems and solutions at http://answers.microsoft.com/en-us/windows/forum/windows8_1-pictures/windows-81-photos-app-does-not-show-any-photos/5b1740bc-d87d-4d07-afe5-c1a60cdecd55?page=6&amp;msgId=9cdf0542-aab0-4a0b-85aa-e9f6d40b64fc

The simplest solution presented was a registry file which has to be reapplied every time LibreOffice is upgraded. The file must contain the following text and be named with a .reg suffix, then double click on it to load it into the registry. You may have to log out and back in, or even restart the computer--I can't remember which I did to get it to work.

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\KindMap]
".wpg"="picture"
".dxf"="picture"
".emf"="picture"
".eps"="picture"
".met"="picture"
".pct"="picture"
".wmf"="picture"
".bmp"="picture"
".cdr"="picture"
".cmx"="picture"
".gif"="picture"
".jpg"="picture"
".jpeg"="picture"
".jpe"="picture"
".pbm"="picture"
".pcx"="picture"
".pgm"="picture"
".png"="picture"
".ppm"="picture"
".psd"="picture"
".ras"="picture"
".svg"="picture"
".tga"="picture"
".tif"="picture"
".tiff"="picture"
".xbm"="picture"
".xpm"="picture"
".pcd"="picture"


I hope this helps, but I am not (yet) sufficiently familiar with Windows internals to explain the problem and the solution presented here.