I assume you are as enthralled with Sudoku as my dear husband is? While invented in the 1780s by Euler, coined "Latin Squares" and then renamed "number place game" in the U.S. in the 1980s, the Japanese have now made it slightly more difficult and have renamed it "sudoku," meaning "number single." An article about it today said its real meaning is "There goes two hours of my life that I'll never get back!"

Why is everyone so taken by it?

Not quite everyone.
I found them to be slightly diverting when they first appeared here but quickly tired of the mainly mechanical process of doing them. (At about the same time that I realised how easy it would be to write a computer program to solve them.)
I now find them rather tedious.
Give me a good cryptic crossword any day.

What Bob said.

Actually, I have never felt drawn to even attempting one such puzzle.

AYIEEEE! It's addictive! Oh lordie, I wish I had never looked. Gaaaaaaaaaaaa

Jo's reaction seems to be how many here in the U.S. are reacting to Sudoko, and across the world, I hear.

It looks rather boring to me as a mathematician. It is slightly more interesting as a computer scientist. Can a purely algorithmic approach be used to generate the answer with a given starting configuration? This reminds me an awful lot of the N-queens problem, and I'll have to examine it when I have more time and energy. It doesn't look to be NP-hard, but you never know with these kind of problems.

I am a wordsmith, not a numerologist! I have never been tempted to try this kind of puzzle.

I once tried an easy one, and found it - well - easy. Except for the need one has to restore order to chaos, or to prove that one is as smart as the puzzle-maker, I'm not sure I see the fascination.

Well, like anything else, some people like it, and others don't. The same goes for word forums, limerick forums, TV shows, etc.

Still this game is the rage around the world. Hab, according the article I posted about it, one of the reasons for its appeal is its simplicity. It's not the kind of thing that I'd go for, but Shu is a real math finatic, and boy is he obsessed with it.

I found it hilarious that pencil sales at British train stations and airports have gone up by as much as 700%...most likely due to Sudoku.

my husband solves these puzzles in about 3 minutes per puzzle. He just "looks" at them, he says, and sees the patterns. Picks up a pencil and fills them in. I have to work at it.

Sean, a mathematical question has been niggling at me.

How many distinct ways are there of filing in the grid? A goodly number of positions are equivalant:

• Swapping digits: replace each 2 with a 1 and each 1 with a 2, or the like
• swaping certain rows: that is, swap rows 1 and 2, or rows 1&3, or 2&3 (similarly with 4,5,6 and 7,8,9)
• similarly swapping columns, or
• similarly swapping a row (or column) of 3x3 "blocks" with another such row (or column).

Ignoring equivalent positions, how many distinct positions are there?

My bet is "not anywhere near as many as you might think." I suspect this is not-of-general-interest, and our discussion should be by PM.

I'll start working it out today. It is a fairly complicated problem, but that graduate combinatorics class I took as a free elective may just start paying off. I'll PM you with my status as I work on it.

quote:

combinatorics

Now what on earth is that?

Combinatorics is just a fancy way to describe counting very complex sets. It actually is a bit more complicated than that, and many combinatorics classes involve graph theory, set theory, and various other mathematical disciplines which aren't really counting, but have many applications in counting. For example, given a type of graph or set with specific properties, how many ways are there to build that graph or set, which is a counting problem. Also, it has many applications in probability theory. For instance, how many ways are there to flip a coin 10 times and get 5 heads and 5 tails? (10 choose 5) The total number of possibilitys is 2^10, so the probability is (10 choose 5) / 2^10 = 252.

It is studied by pure mathematicians and computer scientists, and I have studied it in both contexts. It is a complicated and often counter-intuitive subject, which many students struggle with to a greater extent than any other subject. I had a wonderful professor for a gradudate level combinatorics class, and it was as much learning how to solve difficult problems as it was learning and proving thereoms.