Of Turkish Puzzle Rings

[lethargic_man]

As some of you will remember, I used to have a Turkish Puzzle Ring; it looked like this, but not half as nice (being made out of base metal, and with rough square edges):

(The (apocryphal) story, for those not aware, is that the Turks used to give these to their wives when they went off to fight in the Crusades, so that should their wives prove unfaithful, they'd take their wedding rings off and they'd fall apart, and they'd not be able to get them back together.)

Three and a half years years ago my old ring broke. I'm surprised it's taken me this long to think of it, but I've just got a replacement as a Chanukah present from my parents. The new one looks like this:

I thought: shall I get another four-membered ring? Nah, four-membered rings are boring, and easy. (Though it belatedly strikes me that's a possible advantage: something you can put together in ten seconds is a cool party trick; people are apt to get bored and wander off if your n-membered ring takes five minutes to solve.

On my year off I encountered someone who'd got a six-membered ring before she came to Israel. It came with instructions (which is more than I got with mine, bought from a shop in Jaffa)... but the instructions were for the wrong ring, so when she took it apart, she couldn't get it back together. She spent eight months looking for someone who could help her before she met me. It took me thirty-five minutes to crack—of which thirty minutes were spent figuring out her ring was a mirror-image of mine.

I remembered this when I wore my new ring for the first time, at an engagement party I went to yesterday. My mistake was not to also remember repeatedly spending forever trying, and not always succeeding, to put doseybat's six-membered ring back together, on several occasions.

So rather than sitting down an studying my ring systematically, I assumed I'd be able to crack it fairly quickly, and, showing it to snjstar and her boyfriend, took it off at the party and threw it in the air.

Cue two hours of on-and-off frustrated attempts to put it back together. I kept getting seven rings into place, only to find the eighth one wouldn't go in! Not only that, but at the beginning it stopped me talking to other people, and then later on, I couldn't get out and go the Chanukah party at Moishe House I'd also planned to attend, because I was surrounded by people watching me and offering useless advice, or wanting to have a go themselves, or just wanting to have a look.

Eventually, at the second party, I finally got the thing together, I have no idea how (though something Eliane R. offered as comment turned out to be the final necessary manoeuvre). During the course of this, I made the unpleasant discovery that sterling silver is really soft: twice I had to bend one of the component rings back into shape. I'm not very impressed by this. Making the ring out of sterling silver's all very well, but in this instance it would have benefitted by alloying with something to make the metal harder.

And then this evening, I gave the ring the study it should have had in the first place, and put it together twice to prove I could. The second time I timed myself, and it took four minutes.

Comments

[snjstar.livejournal.com]

Well done!

Ooh. Looks like fun

[bluepork.livejournal.com]

I'm looking forward to having a go at that... shouldn't take more than 10 minutes imo.

On a similar theme, I have two friends who complete Rubiks cubes for fun. (Unlike your approach, they haven't written a computer program, and instead they use their brains alone, so I believe they can truely claim to be able to solve it, a claim you have made which I don't approve of). It usually takes them a few minutes. Anyway, one of them just received a 4x4 version, which adds an extra few layer of complication. I say a few layers, because not only do you have to solve and extra layer on each face, but its not obvious how the faces related to each other in the first place, due to the lack of a fixed central piece. Ha!

Suffice to say he solved that one too, but it took a bit longer.

Re: Ooh. Looks like fun

[lethargic-man.livejournal.com]

No, I never claimed to have solved it. I wrote a computer program that it turned out would, to find one of the manoeuvres I already knew, would have to brute-force search a space 10¹⁰⁰ in size—ever so slightly beyond the range of my machine!

Re: Ooh. Looks like fun

[bluepork.livejournal.com]

Hmm. I recall a conversation in which we discussed this. Maybe it was just the case that we were discussing whether you _could_ legitimately claim to have solved it if the method involved using a computer program which you wrote.

Re: Ooh. Looks like fun

[lethargic-man.livejournal.com]

Yes. Here are the questions I posed (http://groups.google.co.uk/group/alt.fan.pratchett/msg/a7ca4782eec1bd70?dmode=source&output=gplain). And here is the discussion that ensued (http://groups.google.co.uk/group/alt.fan.pratchett/browse_thread/thread/328a46ca6354473c/fd688407fa48dc43?group%3Aalt.fan.pratchett&lnk=nl&) on alt.fan.pratchett (news:alt.fan.pratchett) (starting about a quarter of the way down).

Re: Ooh. Looks like fun

[bluepork.livejournal.com]

Thanks. I'll work my way through all that sometime if I get really really bored one day!

Re: Ooh. Looks like fun

[lethargic-man.livejournal.com]

It's funny you should mention the Cube, actually. I've had a Rubik's Cube sitting on a my desk at work for several years now. A week or two ago, one of the guys who sits next to me picks it up and starts playing with it. Then the next day, he comes in with a Cube of his own. (Apparently he'd been given it by his girlfriend for Christmas.) Then the next day, a second person comes in with a Cube he'd just bought, after watching the two of us. Then the next day the first person said he'd now bought a Cube for his girlfriend.

Meanwhile, I'm back wrestling with mine, for the first time in over ten years, so it's all Cube-mania in BC5 A1 (the internal postcode of my desk in my office).