Mathologer 2
The Mathologer explains how you go about learning to juggle three balls. This complements a video on the mathematics of juggling that is part on the main Mathologer channel.
updated 10 years ago
I finally got around to animating Nicomachus's theorem, one of my all-time favorite mathematical gems. The wiki page is probably the best and most accessible place to look for more information about Nicomachus's theorem tinyurl.com/3h8dk53r
Temper R. Haring suggests to continue the patterns to 4th powers like this:
If the rule is that each row consists of 1 then 2 then 3 numbers and each have to be consecutive uneven numbers then, for n^4 you get:
1 = 1^4
7 + 9 = 2^4
25 + 27 + 29 = 3^4
61 + 63 + 65 + 67 = 4^4
etc.
with the first number of each row being p(p^2-1)+1.
Franz Biscuit adds:
Interesting. So for the general case, the pattern appears to be p^n-p+1 yields the first number of the pth row for the nth power.
Music: Earth, the pale blue dot by Ardie Son
Enjoy!
burkard
Note we are restricting us to asking which pegs can be the sole survivors in the middle of the board. If surviving anywhere else is also an option then some other pegs can also survive.
The music in this clip is I promise by Ian Post.
Enjoy!
Enjoy
Still looking for a bit more critical mass on the Instagram side of things. And so if you are prowling Instagram anyway ... instagram.com/the_real_mathologer
Enjoy.
P.S.: If you use Instagram please drop by the Mathologer testing ground at instagram.com/the_real_mathologer/.
I also like this one:
If there is a God, then ...
0 = ((-1)+1) x (-1) = (-1)x(-1) + 1 x (-1) = (-1)x(-1) - 1
Then shuffling the 1 to the left gives
1 = (-1)x(-1)
Enjoy.
P.S.: If you use Instagram please drop by the Mathologer testing ground at instagram.com/the_real_mathologer/. Also if you like the proof in this video, definitely check out this Mathologer video youtu.be/p-0SOWbzUYI were I showed this proof for the first time.
Enjoy.
P.S.: If you use Instagram please drop by the Mathologer testing ground at instagram.com/the_real_mathologer/. Also if you like the proof in this video, definitely check out this Mathologer video youtu.be/p-0SOWbzUYI were I showed this proof for the first time.
instagram.com/the_real_mathologer
What I like about the solution that I present in this video is that it also gives a complete characterization of those special colorings of square grids on top of giving the answer to the problem. Lots of other nice approaches to this problem are possible.
I'd just like to mention one more approach which I particularly like, not least because it uses a very cute trick that I also talk about in this video
youtu.be/9JN5f7_3YmQ
Basically you prove that you get different color corners in any 4-colouring of a 4x4 grid. Then you scale up the proof as indicated in this diagram
imgur.com/a/affkdH7
So for a special coloring of the 8x8 grid you divide the grid into four 4x4s, and combine the corners of these four 4x4 into another 4x4. Now it's not terribly hard to see that this new 4x4 is also colored in a special way. Therefore its corners, which are also the corners of the 8x8 are have to be of different color. Nice, and in the next step divide a 16x16 into four 8x8s, etc.
Some of you actually argued in this way. One little problem was that most of you who did argue this way thought that it was completely obvious that the new 4x4 carries a special coloring, which is not the case. Remember that you have to check that all 2x2s in this new 4x4 are colored differently. This is really obvious for most of these 2x2s but not for all of them. In particular for the 2x2 consisting of the squares 2,5,4,7 in my diagram you really have to argue separately that these are of different color (e.g. like I did in this video). A second problem is that this approach only captures square grids with sides that are a power of 2 and not all 4n x 4n grids. Anyway nice.
Also you may have noticed while watching my proof that what we are really showing here is that in any special coloring of a 2n x 2m rectangular grid the four corners are of different color.
Anyway, who gets the t-shirt? Bit tricky. The first submission was this:
Joeeeee For the challenge: Same as Pascallian Triangles but for n=4. youtu.be/9JN5f7_3YmQ Where can I get my t-shirt? 😜
So that looks like Joeeeee is on the right track and that his arguments is supposed to be something like what I just outlined. A "bit" short on details though :) The next proof that was submitted and that I thought worked quite well was also along the same lines. This proof was by Tommaso Gianiroio. Again not quite complete, but complete enough to warrant a t-shirt :)
Anyway, I am in a generous mood today and so happy to give a t-shirt to both Joeeeee an Tommaso. Please get in touch with me through a comment on this video and by e-mail.
youtu.be/E2l95ttmJOg
Music: FloatingBranch by Muted
Enjoy!
burkard
in this second part I talk about the MagicTile interface, show you how to design and record algorithms as macro moves, as well as talk you through a complete solution of one of the easy Harlequin edge-turning puzzles (featuring the all-time simplest three-piece cycle algorithm as well as some cute parity problems)
Also check out the following videos for more background information.
"A simple trick to design your own solutions to Rubik’s cubes": youtu.be/-NL76uQOpI0
(for an introduction to designing your own algorithms for solving twisty puzzles)
A mirror paradox, Klein bottles and Rubik's cubes: youtu.be/4XN0V4xHaoQ
(An introduction to what Klein bottles are all about and a bit of fun with putting Rubik’s cubes INTO Klein bottles.)
Cracking the 4D Rubik's Cube with simple 3D tricks: youtu.be/yhPH1369OWc
(Your next challenge after the the Klein Bottle Rubik's cube. Another hall of fame awaits.)
on the main Mathologer channel, this video is a hands-on introduction to the 4D Rubik's cube simulator Magic Cube 4D, with a special focus on building macros for solving this 4D puzzle (for all those of you who would like to give solving the 4D Rubik's cube a go.)
You can download my full set of macros that I put together using the simple methods described in both videos from here:
http://www.qedcat.com/misc/burkard_macros4.log
Having said that I'd like to encourage you all to find and program your own macros. After all, the more work you do in this respect by yourself the closer you will be to being able to say that you solved the 4d Rubik's cube "on your own".
I've also included the macros used in Roice Nelson's published solution (http://superliminal.com/cube/solution/solution.htm ) at the end of my macro file. To understand what most of these algorithms do, you will have to study Roice's write-up. Having said that the algorithm labelled 2nd 4-color series is a very nice example of an elegant short algorithm that twists just one of the corners. Well, worth studying in slow motion. Similarly, the 3rd 3-color algorithm is used for twisting edges (without worrying that it also mucks up some corners).
Enjoy!
Burkard Polster
Here again is the description for the video on the main Mathologer channel.
The vast majority of people who tackle the Rubik's cube never succeed in solving it without looking up somebody else's solution. In this video the Mathologer reveals a simple insight that will enable all those of you who can solve the first layer to design your own full solution for the Rubik's cube, as well as for many other highly symmetric twisty puzzles.
For more details about this really very fundamental idea behind many twisty puzzle solutions have a look at this article by the Mathologer from a couple of years ago http://www.qedcat.com/rubiks_cube
Googling "commutator, Rubik's cube" will also produce links to a lot of very good articles on this topic.
The Rubik's cube animations in this video were produced using the program CubeTwister by Werner Randelshofer: http://www.randelshofer.ch/cubetwister/
Enjoy!
Burkard Polster, Giuseppe Geracitano, Karl and Lara
Enjoy!
Burkard & Giuseppe


