02.28.06
ANN: SMT Competition 2006 rules are out!
The rules for the 2nd SMT Competition are out!
What is SMT?
SMT is an acronym for SAT Modulo Theories, where SAT is the well-known SATisfiability (NP-Complete) problem from Computation. SMT uses SAT to solve formulas which might span multiple theories. Current logics range from Linear Integer Arithmetic (LIA), Linear Real Arithmetic (LRA), Integer Difference Logic (IDL), Real Difference Logic (RDL) to Uninterpreted Functions (UF). More information can be found at the SMT-LIB site.
02.23.06
ANN: PLT Scheme 301.7
The most recent PLT Scheme is now available. The version, although unstable, is available for download and it was just announced by Matthew Flatt.
MzScheme and MrEd are now version 301.7 in the SVN repository trunk.
The change is minor and mostly internal. MzScheme’s C API now includes
scheme_make_prim_closure_w_arity(), which is like
scheme_make_closed_prim_w_arity(), but with a slightly different
calling convention: the closure data is stored inline in the procedure
object, and the procedure object (which includes the closure data) is
passed as the last argument to the procedure’s C function, instead of
passing the closure data as the first argument to the C function. This
change to the calling convention avoids a branch in the interpreter,
and it allows calls to “primitive closures” to use a fast path in JITed
code.Matthew
ANN: New Beta of SchemeUnit
SchemeUnit, the scheme unit test package developed by Noel Welsh arrives to a new beta.
Thanks Noel.
Another beta. Same place:
http://schematics.sf.net/schemeunit.plt
Install using
planet -f schemeunit.plt schematics 2 0
Remove previous betas using
planet -r schematics schemeunit.plt 2 0
What’s new? A conversion script from 1.x to 2.0 (in
plt/convert.ss) Nothing else you’re likely to notice unless
you hack on SchemeUnit.There are three items left on my TODO list. I’d appreciate
feedback from interested parties.1. Make define-assertion also define the shortcut test-X
form. A good idea, but at the moment I lack the energy to
fight with syntax-case. (Note that the shortcut name is
irregular in, for example assert-equal? => test-equal? but
assert => test-assert)2. Change the pompous name assert to the more friendly
check. Requires lots of code changes.3. Use the contract language to define checks on values.
This is a very good idea. However 1) it requires lots of
reworking of SchemeUnit, 2) it requires deep understanding
of how the contract system works, and 3) possibly makes
portability difficult.N.
Mathemagical Meetings
Being my girlfriend an avid student of Mathematics, with a strong and sexy inclination to Algebra and Analysis we both usually spend several hours talking about various subjects. From abelian monoids, groups, rings, hermitian matrices properties, semi-definiteness, other algebra and analysis niceties to algorithms like FourierMotzkin, Barvinok, OmegaTest, etc.
Lately we’ve even scheduled these meetings where we both meet to talk about Mathematics. These are appointed to every Saturday’s early in the morning. So, we have decided some things are terribly nice and ingenious for a wide audience. Things people cannot even imagine how nice it is… surprising results, beautiful theorems… so I will open a new series on this blog: “Mathemagical Meetings”
Hopefully every week you’ll have a summary with the nicest mathematics and computation we talked about that morning.
See you saturday then…
Elections are here again…
For Linux Software!
Vote here!
My votings went to Gentoo Linux Distribution, KDE, Kwin, Kopete, Emacs for almost all types of editing except terminal editing on which I use nano, and GIMP for image editing. Your time to vote…
Brokeback Mountain
Plot Outline:Based on the E. Annie Proulx story about a forbidden and secretive relationship between two cowboys and their lives over the years. A raw, powerful story of two young men, a Wyoming ranch hand and a rodeo cowboy, who meet in the summer of 1963 sheepherding in the harsh, high grasslands of contemporary Wyoming and form an unorthodox yet life-long bond–by turns ecstatic, bitter and conflicted.
Personal Comments:
This movie is one of the most mind-changing experiences you might feel in a theater. I went to see it today during the afternoon and I was not much inspired… I heard it was about the story of two homosexuals who had this secret between them and nobody could know and blablabla… Forget it! Go see it…
Still, I always had something about homosexuals that made me harsh when I talked about them. I think with age that has been changing. Things seem to have become clearer and what was taught me about homosexuals and what my family and society culture made me think about them is being changed as I learn and study and live more. Today this movie also helped me to see things clearly. Sometimes our preconceptions are so deep that makes us blind. Movies like this, which makes us experience mind-changing moments are worth-while and I think there should be more… Obviously, not only about homosexuality but also about other ‘tabu’ subjects that for some reason our society still denies and teaches our teenagers wrongly, I think on this kind of subjects we are going the right way… the change is going slower due to some obstacles in society like the church, politicians, demagogues, etc..
02.22.06
Palestra: Sudoku, futebol, diplomacia e outros aspectos da matemática
O Prof. Jorge Buescu do Departamento de Matemática do Instituto Superior Técnico dará amanhã uma palestra na Faculdade de Ciências da Universidade de Lisboa integrada no 4º Ciclo de Palestras “Matemática, Ciência e Arte”, 2005/2006.
Como devem saber o Prof. Buescu tem uma excelente reputação a nível nacional e internacional, publicou alguns livros na área da divulgação científica, algo em que é exímio. Assim, não convém perder estas oportunidades. Já assisti a várias palestras e nunca saí de lá como se tivesse perdido o meu tempo.
E claro, a parte interessante é que aqueles que não podem ou não têm tempo para se deslocar ao local da palestra podem assistir á mesma, em directo, confortavelmente do vosso emprego/casa pois vai ser transmitida em directo a partir da internet.
02.20.06
Track this…
Tracking people through that mobile devices is kind of scary, but still potentially and technically possible. However, not everybody is able to do that and that makes everybody feel safer. One thing is when the pentagon can track you down from your cell phone, another thing is when your 15 year old neighbor can do it… That’s scary but still that’s a reality this article talks about…
Wonder which site is it…
USR is backstabbing me…
Being security an extremely important issue these days I was not expecting this kind of backstab by USR. A year ago I bought a US Robotics router, specifically U.S. Robotics Broadband Router (Model # 8003 , 1.04 13 ). The firmware version was 1.04.08 at the time but I have updated it to the last version. Still I’ve been having some problems:
- Whenever my brother leaves his PC on downloading during the night for hours and hours long the router decides to stop working so when I get up and wish to connect I usually need to reboot the router.
- Lately, I’ve started to play with webservices and I had to do some forwarding on some ports and play with the firewall, in the Virtual Servers sections… What a mess… First, the interface is extremely ugly with a very bad design and… it doesn’t work… One can easily check that through GRC.
As solution I added my PC as a DMZ, leaving it wide open to the internet and then started to use Shorewall (a layer above iptables to make stuff easier to configure). And now… it’s working great! Damn, I hate that router… if you want something done correctly, do it yourself!
But this I was not expecting… Out of curiosity I checked the source of the page generated by the router interface and:
function submitF(F)
{
var loginflag,loginIP;
var pwd;
loginflag = 0;
loginIP = "0.0.0.0";
pwd = "xxxxxxxxx" ;
if (loginflag == 1)
{
alert("Someone ( " + loginIP + " ) has logged in as an administrator !");
F.submit();
}
if ( F.PSW.value != pwd )
{
alert("Incorrect password!");
F.submit();
}
F.submit();
}
WHERE THAT “xxxxxxxx” IS EXACTLY THE PLAIN TEXT OF MY PASSWORD?!?!?!?!?!
Probably not many people try to access the interface of my router from the outside but still, anyone inside the LAN can do that, i.e., my family. Still, that’s my password for everything and as much as I like my family I don’t want them playing around with my personal stuff! USR never more!
Life at Googleplex
Via Time one can find amazing photos of the life inside Google Headquarters.
A very nice 5 min spender!
