@BillDubuque The trouble is that internetizens are an ungrateful lot. If the site gets hosed somehow, somebody needs to be working on getting it fixed within 5 minutes, or the users will eventually migrate elsewhere. That means either a round-the-clock operations staff or someone on call -- and neither is something you get from volunteer labor, or from some university volunteering the service of their computing dept.
@HenningMakholm I know many people at that company... The government their department with >200 people fuqed up their security certificates completely (blacklisted...) and they "fixed" it with only a couple of people 8-).
Apparently the secret service does not trust their own computer guys as they seem to be a large customer... (if you work there you have to through their security survey which can be the same as the one for the prime minister...).
@JonasTeuwen I think it's because the decisionmakers don't understand what they are paying for, or exactly why having it is a good thing, and consequently can't make proper decisions about what needs to work, what would be nice to have, and what is not needed at all.
@J.M. Sorry, not ten, 10. In some appropriate base.
@HenningMakholm Yea, well, they did this after Diginotar. Was quite funny. The certificates were revoked and blacklisted and the minister was stating on the television: "just click ignore, and it will work!"
And then you have the FoxIT guy in the media who basically said: wa da fuq?
"I know how to resolve hopeless dilemmas by redefining the boundary conditions such that the stupid approach we tried to improve for months actually works as-is".
"I know how to spend weeks and months understanding something horribly complex that mere mortals would run away from screaming -- and then go in and do something about it".
I am still surprised when I see a guy with a math PhD... unzip like ~100 .zip documents which are in the same folder and have a common part in their name manually one-by-one. Why does it not occur to somebody like this that that... could be automated?
@HenningMakholm You mean "cylindrically archive it"?
Now I have to prove that given a metric space $(X,d)$ and a subspace $(Y,d')$, $F'/O'\subset Y$ is closed (open) $\iff$ there exist a closed (open) subset $F \;(O)$ in $(X,d)$ such that $F' (\; O')=Y\cap F(\;O)$.
Let $F \subseteq Y$ be closed. In order to show that $f$ is continuous, we need to show that $f^{-1}(F)$ is closed in $X$. But $f(f^{-1}(F))$ is closed in $Y$, so by hypothesis $f^{-1}(F)$ is closed in $X$.
Well... then it is even worse. Maybe *.zip is too simple a regex.
That math guy also logs in as a root on his Linux machine. The sysadmin quarantined his machine 8-). So now he uses windows instead, where he can just do this.
@PeterTamaroff Well he must have been doing so continually for quite a long time (as opposed to a one off trial like the guy who ask another mans face in florida who was on 'bath salts') because this is definitely premeditated - he purchased his materials over a span of 6 months and booby trapped his house for police.
@J.M. I hadn't either, its quite new I think, the drugs are called 'designer drugs' because they are made carefully from chemical procedures (not extracted from anything natural).
@RagibZaman We've always had designer drugs... :) There's always been an entire community dedicated to molecular tweaking. Here, just a simple substitution can radically affect how it behaves in the brain.
The new part for me is that they have new euphemisms for these things. :D
@J.M. Oh I didn't know about that. I read an article where it said the abuse of designer drugs was relatively recent.
And that it was hard to legislate against them because if they ban a certain chemical, you can just slightly change the molecular structure to something that isn't illegal.
@RagibZaman "if they ban a certain chemical, you can just slightly change the molecular structure to something that isn't illegal." - precisely the impetus. So, you have some of these countries that write laws saying "molecules with this or that group cannot be synthesized without a license". Which can sometimes be overly broad as to be inconvenient for those who have less clandestine motives.
@RagibZaman Yeah, the things going mainstream is relatively new. Ecstasy is the classical example.
(I'm a chemist, so I keep abreast of these things...)
@J.M. At first I thought your reply was a joking followup to Jonas' kickass comment. For me math has always been part pro and part hobby and everywhere in-between. The diversity is nice.
@JM If your are a pharmacist, does the "magnifying" effect of stuff like -xetine together with -idone have to do with the fact that both are metabolized with CYP2D6?
@JM Yes, so, that is the interaction, and not something on neuron level or whatever. Might not be too selective stuff but selective enough not to do that? :-).
@HenryT.Horton Given a metric space $(X,d)$ and a subspace $(Y,d')$, $F'\subset Y$ is closed (open) $\iff$ there exist a closed (open) subset $F$ in $(X,d)$ such that $F'=Y\cap F$.
@JonasTeuwen Maybe they also interact in the brain, but I'm not updated on the cutting-edge research with SSRIs. (I have a number of papers on my to-read list...)
@BillDubuque Not at all. The nice thing about this site is that in RL, I don't really have anybody else to talk about this hobby with, so this site serves me splendidly.
@JM SSRI? Really? Not AP? I thought it was a good idea for a shrink to give every whiner some nice atypical to experience this and know what real misery is.
@JonasTeuwen Most of the cases nowadays are SSRI-triggered, but atypicals can do that too. That's why you have some of these Americans suing the companies after somebody they know went kaput from trying to get rid of the akathisia. For them, it was sucky to trade depression for akathisia...
@PeterTamaroff Hmm, I guess you're right.
@JonasTeuwen ...and it really is messy to clean up after a guy that went *splat*.
@JonasTeuwen Oh, certainly. Atypicals are even more nasty in the grand scheme, but thankfully people on atypicals aren't that many, relative to SSRI users.
@HenryT.Horton your "How did you know my name!?" question brought a very distant memory into my mind.... i dunno if you've ever used AOL Intant Messenger.... but when I used it in college there were these spambots that would send you messages like "Hi <your AIM nickname>", etc.... Sometimes i had fun with them by replying with the question you've asked
So, I have a really dumb question (I don't think it's worth writing it on the site)... Does unitary operation preserve positive-definiteness? That is, if U is a unitary matrix, and A is positive-definite, is UAU* positive-definite?
I'm pretty sure it does, but it's late and my brain is very tired...
the reason i think it does is: A is positive definite iff x*Ax > 0, where x is an arbitrary non-zero vector and * is conjugate transpose
x*U yields just another arbitrary vector, whose conjugate transpose is U*x
so x*UAU*x>0.... does that make sense in a correct way?
@J.M. Oh, no. He finished because his assistant wrote to me, asked me about my postal mailing address and said that she would send Don Knuth's letter to me.
@M.B.M. Not The Art of Computer Programming.
@CLarue In fact, there's no error I found but my mistake.
I'm trying to prove that if $Y$ is a subspace of the metric space $X$ then $O'\subseteq Y$ is open $\iff$ there exists an open subset $O\subseteq X$ such that $O'=Y\cap O$.
@BenjaLim So I'm writing: Assume $O\subset X$ is open in $X$. We must prove $O'=O\cap Y$ is open in $Y$. If $O\cap Y=\varnothing$, we're done, so wlog assume the intersection is not empty.
Here is the definition of a topology. Let $X$ be a set. We call a collection $\tau$ of subsets of $X$ a topology on $X$ if (1) $\emptyset, X \in \tau$, (2) $\tau$ is closed under arbitrary unions , (3) $\tau$ is closed under finite intersections
