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As a young boy in India walking to his school, I used to wonder how drivers could tell if they were on a one-way street. It was ok for vehicles trying to enter the street from the wrong end --- A no-entry sign will prevent them from getting in. But that is not enough, of course. Vehicles coming in from the other side need to be told that they are entering a one-way street too. What if a vehicle on a one-way street suddenly wanted to turn around and go back? But in the city where I come from, the transport department must have wisely decided to save money by relying on people's observational skills. There were no signs at the entrances to one-way streets. There were only ``No-entry'' signs at their exits. I guess it makes sense because the traffic was usually so dense that you can tell one-way streets by just looking at them. There was no chance of traffic ever making it an inch ahead in the wrong direction. However, there is a fine line between impossible and illegal and that is precisely what I set out to exploit. I decided to expose the loophole in the legal system by showing that I couldn't be prosecuted by law although I had done something obviously illegal.

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?

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.

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.

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.

"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.

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.

Last weekend, as I was munching away on a sweet home grown carrot from our own backyard, I let my mind wander with the wind and ponder pointless profoundities. An interesting, but totally useless statistical question occurred to me.

That we are all ultimately made of dust from the distant stars is indisputable. But what, I pondered, might be the odds that an atom of carbon in my crunchy carrot was the same atom in a molecule of CO₂ I had exhaled earlier?