I
just finished the formal lecture-part of the course Projects in
non-commutative geometry (btw. I am completely exhausted after this
afternoon\’s session but hopeful that some students actually may do
something with my crazy ideas), springtime seems to have arrived and
next week the easter-vacation starts so it may be time to have some fun
like making a new webpage (yes, again…). At the moment the main
lievenlb.local page is not really up to standards
and Raf and Hans will be using it soon for the information about the
Liegrits-project (at the moment they just have a beautiful logo). My aim is to make the main page to be the
starting page of the geoMetry site
(guess what M stands for ?) on which I want
to collect as much information as possible on non-commutative geometry.
To get at that info I plan to set some spiders or bots or
scrapers loose on the web (this is just an excuse to force myself
to learn Perl). But it seems one has to follow strict ethical guidelines
in doing so. One of the first sites I want to spider is clearly the arXiv but they have
a scary Robots Beware page! I don\’t know whether their
robots.txt file will allow me to get at any of
their goodies. In a robots.txt file the webmaster can put the
directories on his/her site which are off limits to robots and as I
don\’t want to do anything that may cause that the arXiv is no longer
available to me (or even worse, to the whole department) I better follow
these guidelines. First site on my list to study tomorrow will be The
Web Robots Pages …
neverendingbooks Posts
Yesterday morning I thought that I could use some discussions I had a
week before with Markus Reineke to begin to make sense of one
sentence in Kontsevich’ Arbeitstagung talk Non-commutative smooth
spaces :
It seems plausible that Borcherds’ infinite rank
algebras with Monstrous symmetry can be realized inside Hall-Ringel
algebras for some small smooth noncommutative
spaces
However, as I’m running on a 68K RAM-memory, I
didn’t recall the fine details of all connections between the monster,
moonshine, vertex algebras and the like. Fortunately, there is the vast
amount of knowledge buried in the arXiv and a quick search on Borcherds gave me a
list of 17 papers. Among
these there are some delightful short (3 to 8 pages) expository papers
that gave me a quick recap on things I once must have read but forgot.
Moreover, Richard Borcherds has the gift of writing at the same time
readable and informative papers. If you want to get to the essence of
things in 15 minutes I can recommend What
is a vertex algebra? (“The answer to the question in the title is
that a vertex algebra is really a sort of commutative ring.”), What
is moonshine? (“At the time he discovered these relations, several
people thought it so unlikely that there could be a relation between the
monster and the elliptic modular function that they politely told McKay
that he was talking nonsense.”) and What
is the monster? (“3. It is the automorphism group of the monster
vertex algebra. (This is probably the best answer.)”). Borcherds
maintains also his homepage on which I found a few more (longer)
expository papers : Problems in moonshine and Automorphic forms and Lie algebras. After these
preliminaries it was time for the real goodies such as The
fake monster formal group, Quantum vertex algebras and the like.
After a day of enjoyable reading I think I’m again ‘a point’
wrt. vertex algebras. Unfortunately, I completely forgot what all this
could have to do with Kontsevich’ remark…
If I
ever get our home automation system configured I’ll use my (partly
broken) old iBook as my Indigo-server (or my MisterHouse-server when I brush up my
Perl-knowledge). It should then run quietly put away somewhere and I
don’t want to take it out every time I want to add another routine to
the program.
Fortunately there is a way to do this by turning
the iBook into a VNC-server, where VNC stands for
Virtual Network Computer. Here is how RealVNC describes
it
VNC (Virtual Network Computing) software makes it
possible to view and fully-interact with one computer from any other
computer or mobile device anywhere on the Internet. VNC software is
cross-platform, allowing remote control between different types of
computer. For ultimate simplicity, there is even a Java viewer, so that
any desktop can be controlled remotely from within a browser without
having to install software.
But can all this be done under
Mac OS X without too much hassle? The first step is to download
OSXvnc and install it on the iBook. Some of the
sourceforge-sites do not seem to have this package, but fortunately some
still do. Installation is no problem and when you fire OSXvnc up
you have to fill in a password which you need later to connect to your
OSXvnc-server (the iBook). Most other options one can leave at their
default values but in the Startup-pane it is useful to click on
the Configure Startup Item button. When all this is done, press
the Start button to launch the VNC-server.
Next step is
to go to the computer you want to use to control the VNC-server (an iMac
in my case). On it one needs to install the Chicken of the VNC software which makes the iMac
into a VNC-client. Fire it up and fill out the Host (the name of
your OSXvnc-server, iBookLieven.local in my case) and the
Password (the one of the OSXvnc-server program), press the
Connect button and the screen of your VNC-server will appear
which you can control with your mouse as if you were actually working on
the thing. Very handy as I managed to break the touch-control on my
iBook when installing a new hard-drive and I need the only USB-port to
connect to the X10-network…