# The Spectre of Math

## December 30, 2009

### paranoia … tsa … health care? … crosswalks?

Filed under: Politics — jlebl @ 4:30 pm

So apparently the TSA has gone totally nuts after the christmas bomb incident.

One of the voices of reason is Nate Silver. Nate calculated the (astronomically low) odds of being on one of those flights affected by those 3 attempted terrorist acts over the past 8 years. Do note the word “attempted.” There has not be a single successful one since 2001. So over 8 years, 0 people died. Each year, approximately 45000 Americans die from lack of health insurance. Let me make that bold: Approximately 45000 Americans die from lack of health insurance. Hmm, that’s not enough, let’s make that red and bold and larger: Approximately 45000 Americans die from lack of health insurance.

That’s better. Now notice the difference. Even if we include 2001 in our statistics (and we can include all of recorded terrorism history in the US if we want to), that’s still less than one tenth of the deaths in 10 years (or a hundered years) by terrorism, than in one year by health insurance.

Now for the crosswalks. When my wife interviewed at one company in San Diego, she asked why there wasn’t a crosswalk across the busy street that was between the two buildings the company was renting. Apparently the city refused to put in a crosswalk if there wasn’t a deadly accident on the street.

And now thanks to someone who didn’t manage to blow up his crotch (or actually that’s the only thing he managed to blow up). We won’t be able to use blankets for the last hour of the flight? They will frisk babies (and take their blankets?). They are endangering the health of millions of passengers to protect us from 0 deaths in the past 8 years. Furthermore, it is unlikely that the lack of blankets would have prevented a single terrorism attempt in the entire history of terrorism. I think that’s bordering on criminal on the part of TSA.

But let’s reiterate the main numbers: 45,000 each year die from lack of health insurance, in the past 8 years, nobody died from airplane terror.

## December 26, 2009

### Snowe history forgettism

Filed under: Politics — jlebl @ 5:39 pm

Reading some fun Olympia Snowe quotes. So apparently bringing up the fact that republicans voted for a hugely deficit raising Medicare expansion prompted our Olympia to note that “Dredging up history is not the way to move forward.”

Well, true if you want to work together with someone, it is generally not good to bring up their past, especially if it contradicts their position now. People generally hate be reminded of such things. On the other hand, if the other side is not working with you and is calling you tax-and-spender, then it is just fine. In fact, when somebody accuses you of raising the deficit, that’s what you do: you tell them “WTF, you raised it WAAAAY more on a similar (health) issue just 6 years ago.” “Dredging up history” is talking about republican votes in the 60s.

Of course republicans are not currently in control and hence you can’t point to any legislation they are passing now. So you look at the nearest time that they were in control and you look at that. That’s the best prediction of what the republicans would be doing now. It’s like a baseball player says during the game that the other team sucks at the bat, and then when he is reminded that he sucked even worse in the previous inning, then saying something about “dredging up history” and unfair criticism.

The defense that the economy is now in the shitter and therefore we can’t spend on healthcare is also crap. I mean, in 2003 it was in the shitter just as well. We were looking at two wars (starting one of them), we were barely recovering from 2001 …

## December 24, 2009

### digital signatures … git … and nonsense

Filed under: Hacking,Linux,Technology — jlebl @ 8:30 am

I have created a new gpg key (I have lost my old one somewhere) and made that git tag. But thinking logically I can’t understand the policy of requiring signed tags. If an attacker is able to commit code using the ssh account, he is able to create bogus gpg keys. Unless I am incredibly diligent in maintaining my gpg keys, the signatures are close to worthless. Making a gpg key doesn’t even require one to own the email account. At best the whole setup gives some false sense of security. Unless you are willing to force some draconian measure and only allow trusted signatures, then the whole thing is nonsense. Actually the whole thing is nonsense to begin with. I understand the idea of allowing someone to “sign” a tag in a repository (I understand it, but I think it has little actual utility). But requiring signatures (and thus generating a flood of bogus signatures in the repository) is stupid.

This is the general problem with computer security. Vast majority of users / software ignores security and then a small percentage of users overdo it with paranoia. In fact, this paranoia is usually so great that it makes proper secure procedures too hard for bother for the vast majority of users, hence the system has built in feedback.

Example: If crappy (but easy to set up and use) encryption is available, it will likely result in higher, not lower security. For example: setting up an ssl using webserver is a hassle. Hence, many passwords are sent in the clear (because they are for websites with little interest in high security). The problem is that people hate remembering passwords, hence same passwords are used as for websites which use encryption, and voila. If setting up simple encryption on a webserver would be as simple as tuning parameters, it could be on by default, and most web traffic would be encrypted. You would not have authentication, but it is far harder to impersonate a site, than it is to sniff for passwords sent in the clear. By tying encryption and authentication together, the bar was raised high enough that encryption is rare.

Digitally signed git tags are even less useful. I would bet most people making such tags have unverified digital signatures, simply generating some warm feelings among the paranoid crowd.

## December 23, 2009

### git tag WTF

Filed under: Hacking,Linux,Technology — jlebl @ 9:40 pm

So apparently I cannot make a tag without having some gpg signature nonsense in the gnome git. Given that I don’t use gpg, I now can’t make named tags for releases of genius and gob. At this point I am seriously enough annoyed to just take genius and gob and move both to someplace like sourceforge.

I mean really … WTF … I can add arbitrary code to the project without any sort of signing nonsense, but a simple tag requires my “signature”???? I want to know whatever people running the gnome git are smoking, because that stuff has to be GOOOOOOD.

I can’t fathom the apparent damage someone could do by making some tags on the code that the perpetrator cannot do by changing the code itself.

## December 18, 2009

### real analysis deemed adult content

Filed under: Technology — jlebl @ 7:08 am

Google is not showing any actual ads for the real analysis notes. The problem is probably the URL which is the standard short used by many people “realanal.” I assume that google does not like the common “anal” shortening of “analysis.” Now I wonder how to best fix that without breaking any existing links.

Computers can be so annoying sometimes.

Update: changed the url to /ra/ instead of /realanal/ and added a redirect. That seems to have done the trick. Still I seem to not show up in google searches (I do get some hits from yahoo though). I wonder if that’s related.

## December 16, 2009

### dude! … where’s my healthcare (part deux)

Filed under: Economics,Politics — jlebl @ 10:13 pm

So apparently now we will get a healthcare reform that does two things 1) mandates everyone to have insurance (sounds good) 2) gives subsidies to poor people to buy insurance (sounds good). But …

However, it does nothing to make costs go down. All it does is that the taxpayer pays for some of the costs. The money ending up in the private insurance sector as overhead can grow arbitrarily large as it does now. In fact, perhaps it can grow faster as part of the money is spent “invisibly.” Example (think in recent history if you haven’t seen such an example): If the government starts giving everyone $1000 towards a purchase of a new car to make new cars cheaper, very soon the price of a new car will be$1000 more than it used to be. The car buyer suddenly pays the same, but the car dealers make $1000 extra. And I did say overhead, since the money is not be spent on “healthcare.” It is spent on the insurance sector. So apparently all that we are doing is making sure that the insurance companies are very profitable and can continue to raise costs, need not compete. A good nonprofit (public or not) health insurance is about spreading the cost of healthcare with the minimum amount of overhead (health insurance is purely about spreading the cost, in the end at least slightly more money has to be paid in premiums than is paid for the actual health care). In the current system, the money that flows into the health insurance is a LOT more than flows out (and the difference is rising). There is some sort of a religion in this country that anything that’s a private enterprise is good, and anything that has anything to do with government is bad. If we all believe in capitalism, why are we afraid of competition. If it does happen that the government can run a health insurance better and it drives the private insurers out of business, then so what? Don’t we in the end want our lives to be good? To be able to pursue happiness? Why are so many millions of Americans concerned with the well being of rather a small number of health insurance executives, who might be losing out on their 20 million dollar salaries? The current status quo is good for those few rich executives. The new “reform” is good for them as well. Everyone else is getting screwed over (and many of those people willingly out of paranoid fears about their grandmothers being put in Obama-death-camps). I think perhaps it would be better to let the whole thing go. Leave public option in, let the bill die. The current bill does nothing about the amount of money spent on health insurance and healthcare. It just moves some of the money to be paid from tax revenue. But without any measure to reign in the exponentially rising cost. So all it does is it postpones the day when the system implodes. And makes the implosion probably more spectacular. The insurance will get unaffordable for the average family maybe 5,10,15 years later, but by that time a large part of the bill is also paid by the taxpayer. So not only will we not be able to pay for health care, but we’ll have a huge taxpayer bill. All the time we are feeding an incredibly inefficient system with billions of dollars. I mean have you dealt with a private health insurance lately? The inefficiency of the system is multitudes beyond any braindamage that a government bureaucrat can even begin to imagine. We’re just going to spend more money keeping that system afloat, making the stockholders and executives in those companies rich. In capitalism, one is supposed to get rich by making a superior product. The insurance companies make the worst product imaginable, wrap it in shit and charge an arm and a leg for it, and we’re afraid that they might go under, so we’ll make sure that they don’t have to improve their product? Why are we not afraid of driving private security companies out of business by having a taxpayer paid police force? I mean, poor Tony Soprano, if we make police be government run, maybe he’ll be out of business of “protecting us.” So why not let the bill die. At least the moderate Republicans and the conservative Democrats will have a black eye next election, because trust me, the shit is hitting the fan. By 2010 maybe not yet, but in 2012 or 2014 the situation with healthcare will be so unbearable for such a huge proportion of the population that Republicans will be the ones proposing expanding Medicare. The current bill just moves the fan a little further, but keeps it in the flightpath of the shit, and it throws an extra one or two new pieces of shit at it. ## December 11, 2009 ### Real analysis textbook/notes are done! Filed under: Mathematics,Teaching — jlebl @ 11:47 pm My real analysis text Basic Analysis: Introduction to Real Analysis is done. Well at least I am calling it done. Of course these things are never finished, and I am sure there are typos and mistakes as in any new book. Especially one that has not yet gone through any editorial process 🙂 I will make a web browsable version as well, but later. Now I have to go make 20 copies of the final exam! ## December 10, 2009 ### interesting use of google Filed under: Mathematics,Teaching — jlebl @ 6:08 pm Looking through the logs as to the search terms that come up with the real analysis notes, I noticed several hits that came from google searches where the person simply typed in a problem word for word looking for a solution. For example: In advanced Calculus 1, define f:R converges to R by f(x)= 8x if x is rational and f(x)= 2x^2+8 if x is irrational. Prove from the definition of continuity that f is continuous at 2 and discontinuous at 1. This is exactly the search phrase someone used to find the notes. I wonder if the person really thought that this exact problem and its solution would appear on the web? In a way it is sad that the person doesn’t try to think. Fortunately this exact problem is very unlikely to have an exact solution on the web somewhere (it is a well designed problem for the google age). Hopefully the person will now have to start using the brain. ## December 9, 2009 ### 7 songs for$625000

Filed under: Politics,Technology — jlebl @ 8:38 pm

See here. A modern day Les Miserables in real life. 20 years for stealing a piece of bread. In this case, 10-20 times the average yearly salary for “stealing” 7 songs. Note that the cost of the songs is given current prices $1-$2 per song. Imagine that you shoplift $14 dollars worth of beef jerky in a 7-11. Do you think that you will be charged up to$150000 per each bag of jerky you willfully steal (that’s apparently the penalty for each willful copyright infringement)?

There is something terribly wrong here. Note that O.J. Simpson apparently finally paid only around half a mil for killing someone (though the settlement was for more). And that was a rich person. I’m sure a wrongful death lawsuit against some poor schmuck would be far less. That means that “stealing” 7 songs is apparently worse than killing your wife.

Again, what is the obsession about protecting the recording industry? Why don’t we protect the beef jerky industry in the same way. Actually stealing beef-jerky is worse. The store loses completely. If you copy a song, then there is only a certain probability that you would buy it if you hadn’t copy it. I would say that chance is pretty low. So the recording industry is losing less money than the price of 7 songs.

Then there is this deterrent bullshit. OK, but why is this such a huge problem? Aren’t our priorities all screwed up? I mean, I can think of far more important things we should be deterring people from doing. Entertainment industry is a luxury industry. I mean WTF? Not to mention that there is not even any evidence that any deterrent effect exists.

## December 7, 2009

### Picard’s theorem

Filed under: Mathematics,Teaching — jlebl @ 7:59 pm

Just finished the proof of Picard’s theorem on existence and uniqueness of solutions to ODEs in my real analysis class:

Theorem (Picard). Let $I,J \subset {\mathbb{R}}$ be closed bounded intervals and let $I_0$ and $J_0$ be their interiors. Suppose $F \colon I \times J \to {\mathbb{R}}$ is continuous and Lipschitz in the second variable, that is, there exists a number L such that

$\lvert F(x,y) - F(x,z) \rvert \leq L \lvert y-z \rvert$ for all $y,z \in J$, $x \in I$.

Let $(x_0,y_0) \in I_0 \times J_0$. Then there exists an $h > 0$ and a unique differentiable $f \colon [x_0 - h, x_0 + h] \to {\mathbb{R}}$, such that

$f'(x) = F(x,f(x))$ and $f(x_0) = y_0$.

That was the last lecture for the semester, yay! The proof is essentially the standard one, but of course I don’t use the fixed point theorem on metric spaces since I don’t have that. Convergence and uniqueness is shown purely by methods taught in the class. The only thing which I had to define to state and prove the theorem was continuity in two variables. I think it’s the longest proof in the book, being 2.5 pages long (it’s 12pt font, plus it’s given in a lot of detail).

See the last section in my real analysis notes/book.

I was thinking of using something else such as implicit function theorem or some such, but Picard’s theorem is just cool. Plus the proof uses everything we’ve learned: continuity, derivatives, Riemann integral, uniform convergence, swapping of limits, etc… Plus the proof is a bunch of estimates. It doesn’t get any more “analysis” than that.

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