Sunday, 20 November 2011

Wil Strijbos’ Magic Domino

Start Position
I picked up a copy of Wil Strijbos’ latest IPP exchange puzzle, Magic Domino, from his stand at the Dutch Cube Day. It’s a colourful looking laser-cut puzzle although the aim of the puzzle isn’t immediately obvious, until you read the laminated sheet that comes with it – then it all makes sense: Wil’s taken a simple sliding tile puzzle and combined it with a vanishing leprechaun  / Sam Lloyd’s Get off the Earth illusion!

Hang on, hang on – slow down there just a minute kiddo ... he’s done what?!
Remove the 7 brown dominoes & Magic Domino tile
OK, have a look at the picture above – in the top half you have a field of twelve tiles with holes between them for seven brown dominoes – one of those tiles has the marking “Magic Domino” on it, and you’ll have to trust me here, there’s a hole in the base that allows you to poke out that tile so that you have a sliding tile puzzle – albeit a pretty boring one because all of the tiles are locked together by those brown dominoes ... 

OK so far?

Right, now down the bottom there are eight white dominoes in some spare slots – he thinks of everything does our Wil! Remove the two sets of dominoes from their current resting places – notice there’s one more white domino than brown – worry a little. The holders for the spare dominoes down the bottom have a pair of removable tray parts – take them out and swap them around – did you notice the magic happen just there? There are now only seven slots down the bottom instead of eight – TA-DAA! Place the brown dominoes in those spaces – noticing that they only just fit in – which is all a bit spooky. 
Swap trays & stow brown dominoes...

OK, all of that is really just a little bit of showmanship to prepare you for the main puzzle: now you need to manipulate the sliding tile puzzle to create EIGHT holes for the white dominoes to fit into in such a way that the Magic Domino piece can be replaced (and you’ll notice that because of its little tab on the bottom, it has to go in the middle of the bottom row). 

Right, so not only are you being asked to bend the laws of time and space just a little, you also don’t know what the final position of the domino pieces is going to be – and hence you’re working blind. You’ll probably have noticed that the dominoes aren’t exactly the same size, which gives you a bit of a steer on how you’re going to create that extra space since you can probably guess that the fit for each domino is going to be pretty snug. 

Now make 8 holes for the white dominoes...
You’ll need to make a couple of assumptions and then start experimenting, testing the holes you’ve made as you go along. Mercifully the field of play is a bit smaller than a traditional 15 sliding tile puzzle and that cuts down on the possibilities quite a bit. Once you have the right combinations in the right places, you can pop the Magic Domino tile back into its spot and slot the eight white dominoes into their holes in the top half. 

Time and space duly bent, just a little. 

I found this a really cute implementation of a couple of puzzling ideas that I’d never imagine putting together in the first place. Great idea Wil, and well done for coming up with something totally new! 

One part magic, one part puzzle - all in all, great fun.

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