Bayes theorem history

A fascinating read on the Bayes theorem history:

The German codes, produced by Enigma machines with customizable wheel positions that allowed the codes to be changed rapidly, were considered unbreakable, so nobody was working on them. This attracted Alan Turing to the problem, because he liked solitude. He built a machine that could test different code possibilities, but it was slow. The machine might need four days to test all 336 wheel positions on a particular Enigma code. Until more machines could be built, Turing had to find a way for reducing the burden on the machine.

He used a Bayesian system to guess the letters in an Enigma message, and add more clues as they arrived with new data. With this method he could reduce the number of wheel settings to be tested by his machine from 336 to as few as 18. But soon, Turing realized that he couldn’t compare the probabilities of his hunches without a standard unit of measurement. So, he invented the ‘ban’, defined as “about the smallest change in weight of evidence that is directly perceptible to human intuition.” This unit turned out to be very similar to the bit, the measure of information discovered using Bayes’ Theorem while working for Bell Telephone.

If the whole thing is too much for you, at least read the “Bayes at War” section.

The purpose of an operating system

I came across a good reminder of the operating system’s purpose in this Slashdot comment:

The point of an OS is to make the software independent of the underlying hardware. Windows lost that independence a LONG while ago (Windows NT / 95). Linux still has it because of the underlying design of the whole thing.

The same comment also brought back some memories of the times when I was working as a system administrator at what is now known as PrimeTel.

Move a Windows server – you can be in for a world of hurt unless you want to fresh-deploy it every time. Move a Windows-client, historically you’d be prepared for blue-screens because you have the “wrong” processor type (Intel vs AMD – requires disabling some randomly named service via the recovery console, for example), reinstalling the vast majority of the drivers (probably from a 640×480 safe mode) and even then can’t be guaranteed to get anything back and working – not to mention activation, DRM, different boot hardware (e.g. IDE vs SATA), etc.

Move a Linux server – unless your OWN scripts do something incredibly precise and stupid with an exact piece of hardware, it will just move over. At worst, you’ll have to reassign your eth ports to the names you expect using their MAC address (two seconds in Linux, up to 20 minutes in Windows and a couple of reboots).

It’s been a few years since I did that.  But I remember vividly how we used to move servers from one piece of hardware to another, and since we used a mixture of Windows and Linux servers, the difference was obvious.  With everything else being equal, we could migrate a dozen of Linux servers in two-three hours, moving them in parallel.  Windows machines took days and had to be approached with very little concurrency.

Mind + computer > mind

Obviously, isn’t it?  Well, my brother posted this garbled piece of text, which is supposed to show you how awesome your mind is.

7H15 M3554G3 53RV35 7O PR0V3 H0W 0UR M1ND C4N D0 4M4Z1NG 7H1NG5, 1MPR3551V3 7H1NG5! 1N 7H3 B3G1NN1NG 17 WA5 H4RD BU7 N0W, 0N 7H15 LIN3 Y0UR M1ND 1S R34D1NG 17 4U70M471C4LLY W17H0U7 3V3N 7H1NK1NG 4B0U7 17, B3 PROUD! 0NLY C3R741N P30PL3 C4N R3AD 7H15.
R3-P057 1F U C4N R35D 7H15… !!!

And I agree, it is. But I think that mind with some extra computing power is even better. It took me just a few seconds to instruct my computer how to do a readable translation for me. Much less time than it takes me to read the garbled text.  For those of you with a Linux command line nearby:

$ cat message.txt | tr 715340 TISEAO

For those of you without a shell nearby and not an amazing mind, here is a “deciphered” version of the text:

THIS MESSAGE SERVES TO PROVE HOW OUR MIND CAN DO AMAZING THINGS, IMPRESSIVE THINGS! IN THE BEGINNING IT WAS HARD BUT NOW, ON THIS LINE YOUR MIND IS READING IT AUTOMATICALLY WITHOUT EVEN THINKING ABOUT IT, BE PROUD! ONLY CERTAIN PEOPLE CAN READ THIS.
RE-POST IF U CAN RESD THIS… !!!