Hummings of a Happy Hurkle

One of the great web comics of all time.

http://xkcd.com/386/

But aren’t they all?

Alice, Bob, Carol and David are two parents and their son and daughter. The problem is to work out which is which.

You are told that:

* Bob and Alice are blood relatives.
* David is older than Bob.
* Carol is younger than David.
* Carol is older than Alice.

However, two of these statements are not true! Can you figure out this family?

Solution over the fold.
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And that reminds me of the old geek joke…

She: So, what do you do?

He: I teach Unix.

She: Oh.

[pauses]

She: What do you teach them?

Hmmm.

Ever wondered why English translations of Chinese signs and notices are so bad? And in particular, why they may contain words that are simply not used in polite circles?

Here is an article that explains why, with some detailed analysis and absolutely classic examples. In a word: people relying on bad software.
http://itre.cis.upenn.edu/%7Emyl/languagelog/archives/005195.html

Previous posts have given the rules for the puzzle and explained why traditional solutions fall down. The following is a complete solution. I suggest you don’t look until you have tried to solve the puzzle for yourself.
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There is a commonly given solution to this puzzle that depends on induction, but incorrectly in my view. Here’s why.

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The following logic puzzle is copied verbatim from a particular Web site. I haven’t given a link, and I suggest you give it a try before Googling.

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A horrible disease has broken out in the Kingdom of Faroffia. There is a wonder cure, and you have a 1000 bottles of it which must be distributed today to save the kingdom. Unfortunately, you have just found out that one of the bottles is contaminated with a deadly poison. You have a supply of laboratory mice which can be used to test for the poison, but because it takes some time to have its effect, you only have time to conduct one test.

How many mice do you need in order to find out which is the poisoned bottle?

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You are a young tech just hired by Artslet (your friendly Telco) and obviously someone is out to make your life hard!

You have just assisted your supervisor to lay 1 Km of special cable containing 100 individual wires. As he was about to head off for a very long lunch, he left you the job of tagging all the wires so they can be connected to the correct equipment, promising to buy you a drink if you get there before knock-off time.

Unfortunately, the wires are completely indistinguishable — this would have been a much easier job if you could have done it before the cable was laid!

To assist you in this task you have a large supply of numbered tags, a chart in which you have to record the tags attached to each end of each wire and a simple continuity tester consisting of a battery and a light. If you (say) joined 2 wires together at one end, you could then walk down the other end and test to find out which 2 wires are joined. There is no limit to how many wires you could join and test like this.

The question is: how far are you going to have to walk to tag and record all the wires? What strategy will you employ? Do you have any chance of the supervisor buying you that drink?

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A horrible disease has broken out in the Kingdom of Faroffia. There is a wonder cure, and you have a 1000 bottles of it which must be distributed today to save the kingdom. Unfortunately, you have just found out that one of the bottles is contaminated with a deadly poison. You have a supply of laboratory mice which can be used to test for the poison, but because it takes some time to have its effect, you only have time to conduct one test.

How many mice do you need in order to find out which is the poisoned bottle?