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Comment Re:Because it already is (Score 1) 274

If you carefully read my comment, you will notice that it does not contain any appraisal. Certainly, there are intricate trade-offs involved in coming up with a good policy.

What I wanted to state is the following: Exercising the existing laws that prohibit killing and bombing people is of no use if you want to prevent terrorism. Terrorists do not care about the punishment when they blow themselves up in the end anyway. Thus you need prevention, and prevention only works when you have information.

Comment Because it already is (Score 4, Insightful) 274

Because it already is. And killing people with guns and bombs is something you want to prevent instead of penalizing it after it happens. For this you need the ability to predict what will happen. Such ability is gained from observing the current state of the world (because you cannot observe the future), and drawing inferences from these observations. The more you observe, the more predictive power you gain. Large-scale organized activities (like organized crime or organized terrorism) usually require monetary support, thus observation of monetary transfers gives valuable information about the existence of organized structures, which in turn improves prediction about terroristic (or criminal) activity.

Comment Re:Infinity (Score 1) 1067

I've written algorithms for machine learning, where I'm constantly doing things like multiplying 0 and infinity. And, depending on the situation it is totally clear what the correct result must be (either 0 or infinity).

Take for example computation of the entropy of a deterministic Bernoulli distribution: You have 1 * ln 1 + 0 * ln 0. The correct result is 0.

Mostly I am relying on the proper handling of infinity and NaN by the floating-point implementation; but sometimes I have to catch cases and correct the result by hand.

Comment Re:Casting (Score 1) 757

I was able to avoid casting completely for over two years while working in Scala. Certainly, the kind of work I did somehow supported this.

Only lately I had to resort to casting sometimes. But this happened only when dealing with rather complex types that abstract over nearly arbitrary computations. At one point you reach the ceiling of what is achievable with some fixed type system—and then you need casting.

I am now using shapeless for meta-programming, but I think this is the point where you yearn for more a expressive (dependently typed) type system than the one offered by Scala (or even Haskell). I hope the next generation of programming languages will make this practical.

Comment Super efficient amphibiuous propulsion (Score 1) 73

It sounds like magic! Scientists at Slashdot have invented a mechanism that can propell any vehicle, both under water and on land. The invention works by attaching an external string. An also external human then pulls said string, and the object moves in direction of the string. Youtube video follows.

Comment Re:This is obviously correct (Score 1) 174

In reality there no such thing as a (formal) proof. You cannot prove the simplest things.

You can prove things based on axioms and hypothesis. This works for theoretical settings like mathematics. In reality, even the most simple statement (like "This is an apple.") cannot be verified with certainty (what IS an apple?). Even if you do a DNA analysis of the genome of the object, you have uncertainty in the analysis, e.g. random misreadings of your equipment.

All you can do is be "pretty certain" about something. But that's not a proof.

Comment This is obviously correct (Score 0) 174

Is it possible that using secure email services can be construed as an indicator of being a terrorist?

Take the experiment of drawing a random person. Define two events

  • T - the person is a terrorist
  • X - the person uses encrypted internet messaging

If P(T|X) (probability of the person is a terrorist given he uses encryption) is larger than P(T) (probability of the person being a terrorist using no other evidence), I'd call the fact of using encryption an indicator of being a terrorist.

Any objections?

Of course the "indication strength" might be low. But I think the fact of using encryption increases my belief in someone being a terrorist. And taken together with other observations this might be enough to take according action.

Chemist who falls in acid will be tripping for weeks.