Sunday 1 June 2014

Wire and String from Mr Strijbos

My last Strijbos delivery
You all know about my habit! I have a man who keeps tempting me away from my money! Yes, Mr Strijbos, that would be you! Recently the update that came out had a few nice bits of metal loveliness and, of course, I had to add that to my collection! The 4 piece jigsaw has been quite a hit at work and the Heart in heart puzzle was a big hit with my wife! Who knows whether I will ever get that one back.

Wil knows about my love of disentanglements and is aware that I seem to have become a bit of an expert - I still feel like a beginner but I do appear to have solved quite a lot of them now and the guys at the Midlands Puzzle Parties often give me new ones to try. Wil finds quite a few new ones during his travels and brings a few really good ones back for us to buy. One of the best I have ever tried was the 2 ring teddy which has stumped many many people - both newbies and experienced puzzlers. It was so good that it has made TWO appearances on this blog - here and here.

So whenever one of Wil's updates includes a disentanglement, I have to buy it on the off chance that it may prove as good a challenge as the Teddy! The last update had the Two-U (or U-Two?) in it and of course that ended up winging it's way over the Channel to chez moi. Designed by the famous (or is that infamous) Jean Claude Constantin, it is made of a nicely anodised thick wire with a short length of string and consists of a big ring, 2 U shapes and the string all interlinked such that no single piece can separate. The string is REALLY short so no knots but also very little movement possible. The balls cannot pass through the narrow part of the U's and the ring can't fit through either!

This was one of the first I picked up (I just cannot resist them) and quickly put it down in response to the burning sensation produced by the laser stare! It would have to wait for later.... When later came, I explored a little and got nowhere at all! It is possible to change the configuration quite a bit but topologically nothing changes and they are still all locked together. Some of the moves I tried were highly unlikely to get a solution due to the extreme contortions of the string but I had to try! Over a period of a week, I played and played and got seriously burned - the number F-bombs increased astronomically but I was getting nowhere! One evening in front of the TV I was just fiddling and not doing any really complex moves (or even watching what I was really doing) when the ring suddenly drops into my lap! Another stream of invective and the whole thing is apart! Yessssss!

Grinning at me!
I post a quick pick of my success on facebook and then immediately realise that I have absolutely no idea at all what I had done and in fact because I had not even been looking at it, I did not even know the rough configuration it had been in before the ring popped off! Oops! After a few hours of play, I enlisted the help of some of my puzzle friends on Facebook who had decided to make their own versions of it. Someone did get very close but I just could not get to the start position! I spent days and days and days on it before my breakthrough came! Phew - I was actually planning on giving it to Mr Strijbos to reset so that I could have a crack at it again and pay attention next time. Luckily I no longer need to suffer that humiliation but fully expect him to humiliate me in some other way!

The second puzzle is called the Four-U and I think I am very lucky to own it as it was not part of his update - instead he said that it would hopefully be generally available by the time of the IPP in August. He sent it to me with these words:
"It is a very difficult challenge.
I will be very surprised when you can take it apart and put together again.
Now of course, this is like a red rag to a bull for me! BUT, if Wil thinks it is tough then I am in serious trouble! He is a solving machine! It has a pretty long length of string and certainly is enough to make a proper knot but luckily not long enough for Mrs S to garrotte me - by the time I had gotten to this one, she was pretty pissed off with me! The string is threaded through four of the same U shapes and there is a LOT of movement possible.

During my reassembly trials with the Two-U puzzle, I picked this one up several times and managed to do some very interesting things with it and noticed some really interesting properties! But despite all I saw I began to get fairly knotted and always backed off before I went that little bit too far.

Whilst on call on Sunday night, I had it sitting in front of me whilst watching TV and just mentally made some moves in my head. There's not a lot in my head most of the time but this time I realised something very special could happen with a certain move so I reached out and did it - studying the conformation, I realised that I should have learned something from the Two-U - they are not the same but the share a feature or two and I tried a new idea. Nothing fell off, but there was a subtle change which did not appear to me straight away. I undid all the moves I had done and..... one of the U's fell off! Wha....How....? Quickly, I reversed my steps and at that point I noticed the subtlety mentioned before. I realised that I had done something very interesting and quickly worked out what it was before reversing all the way back to the beginning!

I sat and stared at it for a while before plucking up the courage to have another go. This time I was VERY careful to pay attention to the exact orientation and voila! A knot!!! Something went wrong! Backtracking led me to stare fixedly at it for a while before realising just how subtle the change had been. This time I tried my move in a different direction and there I was - another series of moves and one U was off. OK! Time to do it again but with less pieces and again with even less and finally we have:

Another one grinning at me!
Oh boy! That was incredible! I agree with Wil - it is a really tough puzzle - mainly because of the extreme subtlety required of the movements! I have to say that this one is right up there with the 2 ring teddy for enjoyment and the Aha moment. I really hope that there are more like this coming out!

If you get a chance when Wil releases it to the unsuspecting world - buy it! It's brilliant! If you haven't bought the Two-U yet then it is also absolutely fantastic! I will be carrying these with me for quite a while! Thanks Wil!

Just another quick notice - this weekend Wil has released onto an unsuspecting world his latest puzzle design - The Egg! Actually, it's not new - it dates back to 1986 but was not mass produced because it was too difficult. Luckily in the 21st century we have modern manufacturing techniques and it's available again! It's NOT cheap and but it will be fun - mine is on it's way to me already. Don't tell Mrs S as she doesn't need to know!

Hopefully I'll manage this!


  1. Hi Kevin,
    I also found the U-Two to be a tough nut to crack and even harder to uncrack.

    After 2 weeks I finally found the right sequence of moves to reassemble it. Now I can do it blindfolded. I've got the remainder of J. C. Constantin's wire and rope puzzles on order from W. Strijbos. I hope the 4-You is included in that shipment.

    Peter / pcad

    1. Hi Peter,
      Wil did copy me in to your email. I am very impressed that you solved two-U. It is a very tough one to get your head around. You will love the four-U!

      Do let me know which other JCC wire and string puzzles you get!

    2. Dimiter Vakarelov15 June 2014 at 16:08

      Hi Kevin, 4-U is indeed a wonderful puzzle. Thanks for publishing it. I copied it for me and started playing with it. First I learned the version of 2-U (version with only two U details) : easy! Then 3-U, not so easy, but the method was a little update of that of 2-U. The case of 4-U, however, was difficult and I was not able to use my knowledge for 3-U. Finally I found a solution, but this was not an update of the solution of 3-U. I wander if there is a recursive algorithm for “n-U” (n=2,3,4, 5…). I hope there is. What do you think?

    3. Hi Dimiter,
      I'm flattered that you read my little puzzle blog! I don't think there is a recursive algorithm, unfortunately! But a few techniques are usable from both!

    4. Dimiter Vakarelov16 June 2014 at 08:51

      Hi, Yesterday I solved suddenly the 5-U and now I am trying to repeat the solution. I think that “n-U” has a solution for all n.

    5. Wow! You are quick! I would be interested to hear your exposition on puzzles of level n!
      The morphology of 2-U is different to 4-U and hence I thought they could not be generalised. But I think you could make a 4-U puzzle with many more Us and have a general solution.

    6. Hi Kevin, I have just found a recursive algorithm for “n-U” working for arbitrary n. I experimented with n=6, 7. The idea is simple: by several manipulations with the rope and the first U one can separate the chain into two consecutive chains on the rope consisting one with (n-2) U details and another one with 2 U . Then apply the algorithm for “2-U” and separate the two U from the rope. In this way you obtain a shorter chain and repeat the recursion in the same way. I learned that Mr Strijbos ask puzzlers not to disclose publicly the solutions of his puzzles, so I think this partial disclosure does not destroy your pleasure to find by yourself the recursive procedure. I wonder if he expected that his puzzle can be generalized for arbitrary “n”. Kevin, you can take two additional U from the other puzzle with the ring. Pleasant puzzling, Dimiter.

    7. That's very impressive! I will need to get my U's from 2-U and make a 5 & 6-U puzzle. I do worry that the string will not be long enough.

  2. They look amazing! I must get those string puzzles. :)

    1. I am sure that Wil has some in stock - he also has some other variants available too which are just as much fun!

    2. I looked (if I got the correct site), but there seem to be no availables. :(
      Anyway, I am waiting for another delivery now, so maybe some time later in the year I will look for these two. :)

    3. If you email Wil then I'm sure he will have some!