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January 1, 1998

Is Learning Unix Worth the Time?

First appeared in High Technology Careers, Vol 15(2w), p.26

It seems Ken Thompson, one of the people who wrote Unix, was asked what he thought of the date-rollover problem in Unix (In the year 2038, the Unix date value wraps around to 0). His reply was that he didn't care as he was going to be dead by then. A speaker at the UniForum NZ 97 conference at Rotorua quoted this anecdote. When I mentioned this to a friend, he said that this speaks a great deal for Unix since the questioner implicitly assumed that Unix was still going to be around in 2038. Well is it? Is it worthwhile learning Unix skills and still be employable in the decades to come?

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May 1, 1999

The Troublesome Toilet Seat - Up or Down?

Why would someone start a serious study of something so silly? That's precisely what I thought until I noticed that this seems to be a real problem in many households, at least as evidenced by popular sitcoms on TV such as ABC's ``Home improvement'' and NBC's ``3rd rock from the Sun''. This is what ultimately stimulated my interest in this seemingly trivial issue.

Click here if you just want to run the computer simulation.

1. Introduction

In spite of Faye's repeated insistence that Mike leave the toilet seat down, Mike made the unfortunate mistake of accidentally leaving it up one day, only to suffer its dire consequences. Faye threw such a fit that Mike had to sleep on the couch almost that whole week until he made it up to her.
Most of us who read the above passage are probably sympathetic toward Mike, but strangely, not as harsh in our judgment of Faye as we should be. Consider instead the following situation:
In spite of Mary's repeated insistence that Peter bring her a bunch of red roses every day on his way home from work, Peter made the unfortunate mistake of forgetting to do so one day, only to suffer its dire consequences. Mary threw such a fit that Peter had to sleep on the couch almost that whole week, until he made it up to her.

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July 7, 1999

The Clever Widows of Fornicalia and the Stobon Oracle

July 7, 1999: There is a more recent version of this document with a Prolog implementation of the proof by Ray Kemp. It is available in Postscript format (140K) and can be downloaded from here.

In a certain village on the remote plains of Fornicalia there exist some men who are having affairs with the wives of other men. Now there is a gruesome custom in this village which requires a woman to kill her husband the morning after she discovers that he is having an affair with another woman. It also happens that every woman knows whether every other man is having an affair or not except her own husband.1 So life in this village goes on peacefully since no woman can know for sure that her own husband is cheating on her. Unfortunately, an Oracle from the pure and untainted shores of distant Stobon visits the village one day and proclaims that at least one man in this village is having an affair. What happens after this?

Readers are urged to think of a solution themselves before proceeding further. We first present the solution and its proof and finally go on to discuss the information theoretic aspects of this remarkable problem.2 A similar treatment of this and some other aspects of the puzzle can also be found in Moses et al. (1986) and Halpern and Moses (1990), both of which also cite other sources where further discussion of the topic can be found.

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November 18, 2006

The CPA Nube Lube Tube

Grease to ease the transition of newbies into the fascinating world of Cost-Per-Action (CPA) advertising

First appeared in San Jose Mercury News Forums, Nov 18, 2006.

Consider the following ad, the likes of which we are all only too used to routing promptly into our spam buckets.

"The sex of your baby predicted CHEEP! Guaranteed Results. 150% REFUND for wrong predictions"

There you have it - a simple and sweet business plan if ever there was one. But people who ponder can promptly peer past its imposturous garb. This is just gambling in disguise. Suppose the service costs $1.00 and a thousand naive couples paid for it. On average, five hundred of them will receive a refund of $1.50; the rest will presumably be happy to have been told the sex of their baby. Despite the refunds, however, the service provider is $250 better off than she was before, and for no more effort than flipping a coin for each customer. Immediately, one can tell that the scheme is a rip-off, aimed at defrauding innocent parents-to-be of precious baby-dollars.

To the uninitiated, that is exactly how CPA advertising is being framed by ad-networks steeped in profiting from traditional methods: "Give us your ads. We'll show them. You only pay for ads that result in a sale, but not a cent on the rest." On the surface, yes; this does look like a scam. But fortunately, this is not what CPA is about. In fact, CPA represents the exact opposite. CPA ad-networks don't just flip a coin to show an ad. Considerable effort and investment go into determining where each ad is most likely to appeal, and, of course, web real-estate on which to show ads does not come free either. A CPA network will actually "lose" money if you don't make it and therefore it is in their best interest to make sure you are successful.

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July 29, 2007

A Metaphorical Essay - Google News, Air, and TCP/IP

If you could see the individual molecules of air in a perfectly still room, you would see that the molecules are anything but still. They are moving in all directions, apparently randomly. Each has its own spin, and its own story to tell. Yet the room itself, made up of millions of these molecules, has the picture of perfect calmness as though nothing in it is even stirring. In the calm of this room lies buried the solution to the most pressing problem in objective journalism.

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August 18, 2007

Fixing Fontconfig on Linux with strace (Unable to load default config file)

Today, Linux is a beautiful thing and I typically waste no opportunity to evangelize it to friends considering a new desktop purchase. I mean, if the average user today calculates how much of his or her computer time is spent either on-line or within office applications, it seems like common-sense to buy a Linux desktop with Firefox and Open Office rather than buy expensive Microsoft products. Homer Simpson captures the sentiment best in the opening line of the latest Bart Simpson flick. Why would someone pay hard-earned cash to get something we can get for free? We're all giant suckers!

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January 8, 2008

On Data Analysis

Forget OLAP cubes and pivot tables! As is the case most of the time, 90% of the insight can be gleaned from very simple data plots. To be sure, the remaining 10% does shed valuable new light, but is also orders of magnitude relatively more tedious to distill.

One of my favorite tools for performing quick sanity checks on data and even for inferring high-level trends is a histogram; it simply partitions your data points into a fixed number of buckets, with each bucket holding points that fall within a given range. The resultant bucket sizes are then available to eye-ball, often plotted as bars whose lengths are proportional to the number of elements in the corresponding buckets.

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February 20, 2008

How to browse the Internet perfectly anonymously

Related website: Pippini.com
"Tell me Mr. Jones," said the public prosecutor, "All the evidence points to the fact that you were indeed contemplating the murder of your lover on that night. Were you not? Remember that you are under oath, and that your polygraph results have betrayed your innermost thoughts. You had the motive, ability and, in your judgment, sufficient anonymity to carry out the macabre act with impunity. And I admit that were it not for this mass of incontrovertible evidence we uncovered by following your intent, you might well have succeeded in pulling the wool over our eyes! Is this not what you are thinking?"
There it is. Fragment from a mystery novel as it were, when you gauge your own mental reaction as you read the passage, you will find it to be a clear example: Most reasonable people would not think twice about sanctioning techniques, including the administration of polygraph tests, that authorities may use to probe into and conclude on the conents of that innermost repository of our private thoughts - our mind. Yet, it appears unreasonable to most of us if authorities claim to have the ability, much less to use it, to determine probable intent in criminal behavior from one's behavior on the Internet. Is the Internet that different in people's perceptions as a place where absolute anonymity may be enjoyed regardless of disposition and intent? Indeed, do people honestly believe it is ok to probe one's mind, but not one's online behavior?

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February 22, 2008

Calculating the median of a MySql table column

My staff are amazingly efficient at automating the various slices and dices of data for me. They like to do it in SQL scripts, MySql in specific, and as a consequence, the data I want to look at is automatically generated every night into various MySql tables. I, in turn, have my own scripts, and ye old console, to extract the information I want. However, one issue that bugged me early on was getting at the median of a set of numbers.

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