thnik again!

I’ve always been amazed at the power and the effectiveness of the simulation technique, and whenever possible I’ve used simulations in mathematics. Since I’ve always loved sport as well, I decided a few years back to see how I could put them together to produce a maths-based World Cup simulation for teachers and pupils to use. The simulation proved very popular in primary and secondary schools, and this article is a revised version of what I wrote then. - Alan Parr

Here is Parr’s article on how you can simulate the World Cup with your students or friends.

For the last three years, I.B.M. scientists have been developing what they expect will be the world’s most advanced “question answering” machine, able to understand a question posed in everyday human elocution — “natural language,” as computer scientists call it — and respond with a precise, factual answer.  - Read more | Video | IBM

Try to beat IBM’s answering machine at Jeopardy here.

Twiddle is a tile-rearrangement puzzle, you are given a grid of square tiles, each containing a number, and your aim is to arrange the numbers into ascending order.

Play it here.

Play it here, and let us know how it went.

Slide the grid squares around so that they all join up into a single connected network with no loops. Click on the arrows at the edges of the grid to move a row or column left, right, up or down. The square that falls off the end of the row comes back on the other end. Squares connected to the middle square are lit up. Aim to light up every square in the grid (not just the endpoint blobs). Connecting across a red barrier line is forbidden. On harder levels, there are fewer barriers, which makes it harder rather than easier!

Play it here.

You have a grid of squares, some light and some dark. Your aim is to light all the squares up at the same time. You can choose any square and flip its state from light to dark or dark to light, but when you do so, other squares around it change state as well.

Each square contains a small diagram showing which other squares change when you flip it.

Play it here, or download it.

A number of balls are hidden in a rectangular arena. You have to deduce the positions of the balls by firing lasers positioned at the edges of the arena and observing how their beams are deflected.

Play it here or download it here.

Wikipedia has a long article about the game.

Save Our Dumb Planet here.

Draw horizontal or vertical bridges to link up all the islands. Bridges may be single or double; they may not cross; the islands must all end up connected to each other; the number in each island must match the number of bridges that end at that island (counting double bridges as two). Note that loops of bridges are permitted.

From Simon Tatham’s Portable Puzzle Collection. Play it here.

Colour the map with four colours, so that no two adjacent regions have the same colour.

Nice interface. My four-year old son likes it a lot.

From Simon Tatham’s Portable Puzzle Collection. Play it here.