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Wooden Jigsaws

Leave a jigsaw unfinished on a table, and my mother-in-law will be attracted to it like a moth to a flame. She says she hates the 1000-piece puzzles that are impossible to solve, but really you can tell that she likes those the most. She'll find a single piece to place, declare victory for the day, and then leave the puzzle in its slightly-less-jumbled state. Puzzles are to savor over time.

So for Grandma's birthday we decided to give her a custom picture puzzle depicting the kids...

Compulsory Chinese in Panama

Thought this was an interesting news item: Panama is moving to make the teaching of Mandarin compulsory in all schools.

Welcome to the 21st century.

Brooks on Obama

A perceptive column on Obama by David Brooks in todays NYT. Brooks contemplates the exposure, isolation and the madness of the presidency, and concludes that among the Democrats, Obama is best-suited for the job.

Obama is an inner-directed man in a profession filled with insecure outer-directed ones.... Like most of the rival campaigns, I’ve been poring over press clippings from Obama’s past, looking for inconsistencies and flip-flops. There are virtually none. The unity speech he gives on the stump today is essentially the same speech that he gave at the Democratic convention in 2004, and it’s the same sort of speech he gave to Illinois legislators and Harvard Law students in the decades before that. He has a core, and was able to maintain his equipoise, for example, even as his campaign stagnated through the summer and fall.

Worth a read.

Out of Stock Toys

Can't find a Wii? Get a DS instead.

I can vouch for the fact that the DS can be just as fun as the Wii, especially if you get a few. Mario Kart is great on the DS - for the price of the Wii and a lot less headache, you can fill the room with screaming jumping kids, each driving their own kart on their own screen.

I wonder how many Christmas shoppers are making that substitution.

From Reuters today:

The DS has been the best-selling piece of gaming hardware this year, moving 1.5 million units in November, according to market research firm NPD.... "The DS continues to perform exceptionally well, with some retailers voicing concerns about DS inventory going into the holiday," Fils-Aime said.

Is the DS going out of stock too? I can still find it at Costco, no problemo.

Meanwhile, the Amazon order for the Pleo I placed a month ago has been cancelled because Ugobe can't seem to get their manufacturing going. Pleo is not a case of a company unable to keep up with millions of units of demand; it's a case of a company having trouble getting their manufacturing started in the first place. A real mess-up.

Oh well. Any suggestions on what to substitute for a child who wants a robot? Maybe some Legos...

Handshaking Puzzles

While you are going to holiday parties, you might want to count handshakes, because you will find some puzzling properties. Here are two handshaking puzzles.

Party Parity

Puzzle number one is from Shklarsky's USSR Olympiad Problem Book. It's a proof puzzle.

Why must an even number of people at any party shake hands with an odd number of others?

That is, if you count the number of people who have shaken hands with an odd number of people, the number will always be even...

The fun part of this puzzle is to actually test it out with any combination of handshaking. It is absolutely true!

Pair Party

The puzzling part of puzzle number two is that it is possible at all. Here it is:

You and your spouse invite ten other couples to a dinner party, and the partygoers shake hands with people they have never met before. At the end of the party (perhaps pursuing the parity problem) you ask everybody, including your spouse, to tell you how many people they shook hands with. Interestingly, everybody reports shaking hands with a different number of people. Of course, nobody shook hands with their partner.

The question is, with how many people did your spouse shake hands?

This puzzle, from Paul Zeitz's excellent The Art and Craft of Problem Solving, hinges on the fact that you don't ask yourself the question.

Heidi says, "of course your wife shakes everybody's hand, because she's the hostess," but it's not that kind of question. It's a math puzzle!