Xenon, Tantalum and Fermium

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Pio2001
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Xenon, Tantalum and Fermium

Post by Pio2001 » September 24th, 2012, 5:51 pm

IMG_1447.jpg
IMG_1447.jpg (42.74 KiB) Viewed 11695 times
Wiki page :
http://www.puzzle-place.com/wiki/Xenon
http://www.puzzle-place.com/wiki/Tantalum
http://www.puzzle-place.com/wiki/Fermium

Type : High level board burrs
Estimated solving time (taking apart) :
Beginner : 10 hours
Casual puzzlist : 5 hours
Expert puzzlist : 3 hours

The + : Exceptionnally well designed disassembling sequences (until the first piece is removed). Excellent manufacturing quality.
The - : Once the first piece is out, the rest of the disassembling sequence is chaotic. Reassembling the puzzle is difficult.

My rating : 5/5


The Xenon, the Tantalum and the Fermium are three different versions of a single design, by Donald Osselaer. It is a "board burr", that is a burr puzzle made of interlocking boards. It was first designed completely by hand, without the help of any real-world model, not to mention a computer. And that is probably why it is so interesting.
The number of moves needed to remove the first piece of the puzzles are respectively 42, 73 and 100. However, they are perfectly structured according to a certain plan that Donald had in mind from the beginning. It's not just a random succession of moves that has to be guessed by trial and error.

The name of the puzzles is chosen according to the atomic number of the chemical elements. 54 and 73 for xenon and tantalum, which represent the number of moves to get the first piece out without performing any rotation. 100 is the atomic number of the fermium, wich is the number of moves to get the first piece out using a rotation.

The goal is to disassemble the puzzle. To put it back together was not part of the initial challenge, and is usually done with the help of a computer running the Burrtools software, unless you learn by heart the position of each board.

In the beginning, I had no idea of what to do. I explored the possible moves from the start position, and it quickly turned out that one of them lead much farther than the others. This path, made of a long succession of moves, is not completely forced. You always have the choice between some minor variations, but these variations are not confusing enough to get someone lost.
Eventually, the logical sequence comes to an end. On the Xenon and Fermium models, a given piece can get out thanks to a rotation. It doesn't make much difference if you perform this rotation or not in the Fermium. However, in the Xenon, without using this rotation, things get quite complicated. You have 12 more moves to find, and they don't belong to the same logic at all.
In the Tantalum, the rotation is impossible, but the final part of the sequence is not as confusing as in the Xenon. Last, let's mention that a second version of the Fermium was designed by Donal Osselaer, but never manufactured. In this version, the rotation was forced. There is no other way to remove any piece, and according to the software, the puzzle has no solution. It follows that on this one, you would have to be extra careful when you disassemble it if you want to have a chance to get it back together one day! A third and final version was then designed, that is quite the same, but without the extra colours to force the solution. It was not manufactured.

The removal of the next pieces was not part of the initial design. It follows that the next moves to perfom do not obey to any particular logic. On the Fermium, it is escpecially difficult to get a second piece out. I'd say that it would be insanely difficult if the information that the number of moves needed is 80 was not available. Knowing this, it becomes obvious that you have to play back the sequence in the reverse order. That's the only way to perform so many moves.

The manufacturing quality is excellent for board burrs. All angles are beveled, which is very useful in order to perform smooth movements. The pieces are assembled using mortices for maximal sturdyness, and you don't even have to be especially careful to make any legal move. They come naturally, unlike in larger board burrs like the Ultraburr and the Millenium, where the pieces must be properly aligned for any move to be performed.

Two versions of the Xenon were made. The one in the first picture above is in maple, cherry and walnut. Here is the other one, in difou, padauk and wacapou :
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The Tantalum was made in beech, cherry and walnut. Beech is darker than maple, but more textured. Fermium use the same woods as Tantalum, but with a part of the central pieces using an alternative colour. This was required to flag the central pieces, in order to avoid other, easier solutions, to be possible.

Because of the real reflexion that was put into the conception of these puzzles, and that results in very interesting disassembling sequences, I give them 5/5.


Link to the discussion about the conception of these puzzles : http://forum.johnrausch.com/cgi-bin/ult ... 1&t=000336

Related puzzles by the same author :
Natrium : http://www.puzzle-place.com/wiki/Natrium
Silicium : http://puzzlewillbeplayed.com/9BoardBurr/Silicium/
Ultraburr : http://www.puzzle-place.com/wiki/Ultraburr
Millenium : http://www.puzzle-place.com/wiki/Millenium

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Pio2001
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Re: Xenon, Tantalum and Fermium

Post by Pio2001 » September 25th, 2012, 10:30 pm

In addition to the above review, I'd say that out of the three models, my preferred one is the Tantalum, because it is the one that need the least random search in adition to the central logic sequence created by Donald.
In the Fermium, the way to get the second piece out doesn't belong to the same logic at all, and I find it more difficult to remember how to reassemble the Xenon than the Tantalum.

Donald
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Joined: June 24th, 2012, 6:51 pm

Re: Xenon, Tantalum and Fermium

Post by Donald » May 24th, 2013, 10:49 pm

Thanks for reviewing my puzzles, Guillaume.
I'm glad people enjoy the creations I hurt my brain over night after night :)

I have a little to say about the Fermium and the unlocking of the second piece, though.
You find it hard and illogical, whereas I personally find it very logical and easy, so I'll try to explain.
Bear with me:

The first 100 moves are all very logical and iterative.
All of those moves are performed without ever moving the "first piece" (the first piece which comes out).
So basically, the other 8 pieces serve as a giant lock that holds the "first piece" in place.
This means that, even with the first piece removed, the puzzle is very likely to remain almost exactly the same.
Just without the "first piece" in place.
So if you consider that, you can start thinking about a piece that can be removed because the first piece is now out.
So personally I find it very logical to start "back-tracking" through the solution until a state is achieved in which this is possible.
The two "gate pieces" can both move 2 steps backward and release the front "combination piece" (as I call them)
This is the only option, because none of the other pieces are released by removing the "first piece" but the "combination pieces" and only the front one can be released by the "gate pieces" because they can only move in that direction enough to do so.
The only reason why this doesn't work from the beginning is because the "first piece" is there to block it.
Once it's gone, this is no longer the case, and so you simply need to bring the two "locking pieces" in their original positions to allow the front "combination piece" to slide through while the two "gate pieces" are both moved to the back.

I made a video last year of the disassembly:
http://www.youtube.com/watch?v=il4zyJZQ0Qk
At around the 5 minute mark the "locking pieces" are in their original positions and I start moving the "gate pieces" backwards to release the front "combination piece".

I hope that was explained well enough :)

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Re: Xenon, Tantalum and Fermium

Post by Pio2001 » May 27th, 2013, 12:05 pm

Hi Donald,
Thank you for the interesting explanations. This is a point that is common to all puzzles : it is always possible to solve them "by chance" if we don't understand the logic. In high level burrs, this is always a risk.

The puzzles then look more boring than they should. In fact, in 2010, when I solved my second high level burr (Condor's Peeper), I wrote a document explaning all the details of the solution. I think that many burrs would deserve a manual explaining the solution.
Bill Cutler's burrs like The Cube, or Hectix Revisited come with very interesting booklets explaining how the puzzle was created, how it works, its geometric properties (Hectix Revisited), or giving progressive clues in order to start the resolution (The Cube).

In my evaluations, it is probable that in many cases, I overlooked something interesting in the puzzle, exactly like with the Fermium, and gave a poor appreciation to a puzzle that is in fact very interesting.

Nicolas
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Joined: January 31st, 2015, 9:09 pm

Re: Xenon, Tantalum and Fermium

Post by Nicolas » April 25th, 2015, 12:16 am

Guilllaume have lent me his Fermium, it's my first board burr...

YAHOOOOOOO !
I've just managed to remove the "second piece" ! about 4 hour for the first piece, and four more for the second :crazy:

Donald, I would say that when you know the solution and understand it, it becomes more obvius... I've just read your explaination, now my second piece is out and it seems obvius, it was not for four hours. Why ?

Because the 2 step backward mouvement of the upper "gate pieces" was never done before, so I did'nt think of it, and I was sure that the "second piece" could'nt remove... And there is so many interesting mouvements to explore with the "first piece" out, that I was attracted to try them, even I did'nt see where it could lead.

Actually, for the "first" and the "second piece" it takes me time to view the solving mouvement. It was not "by chance", but I had to be close to the mouvement to see it, despite having look after it...

So now it's very obvius !!! :D

It's late and I will compleate my post later... :yawn: :clap:

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Pio2001
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Re: Xenon, Tantalum and Fermium

Post by Pio2001 » May 1st, 2015, 11:49 pm

Congratulations, Nicolas !...

I'm starting to wonder what will be the most complicated puzzle that you can solve ! I've been beaten by the Muff (93 moves 18 piece burr by Alfons Eyckmans) and the Morito (155 moves 18 piece caged burr by Stéphane Chomine, based on a Stefan Baumegger design).
I know that the Muff have been solved by Aaron, but there has been too few copies of the Morito manufactured to know what other people think of it. I think that it is solvable, but it is just above my skills.

Nicolas
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Re: Xenon, Tantalum and Fermium

Post by Nicolas » May 11th, 2015, 11:06 pm

Thanks a lot Guillaume to have lend me few of your puzzles !!! I love

Ok, so I think now that to know the number of moves to solve a difficult puzzle helps a lot. It's very different to go without these few numbers, and the second piece in Fermium is the perfect exemple. If you now that this second number is 95 or about 95 it's much easier.

When Guillaume you have lend me your Fermium you told me quickly that for the second move we have to go backward. I didn't want to use entirely this information so I've tried to explore the puzzle without going back to the very beginning.
Without knowing this information, I would probably have spent more time in this exploration, so more than 4 hours for this second move. I did'nt know that the second number is exactly "95", if I've known, I would have probably gone back quickly to the beginning.

I think this is not very important for the first piece, but more for the followings. Particularly when there are many possible moves after few pieces removed. For exemple, in a puzzle, if you have removed 4 pieces and you stay in a labyrinth, it's a very good clue to know the number of moves between the last piece and the folowing.

So the evaluate the level of a puzzle we have to take in account the knowing of the level numbers :)

:wave:

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