British humour never fails to let me know I have asthma.
@N8ive49er
3 жыл бұрын
Brilliant logic with this solve. I attempted this puzzle for a little over an hour and couldn't do it. I then allowed myself the benefit of using the '3647' x wings you discovered and still couldn't do it.
@andreww4473
5 жыл бұрын
Couldn't have done that in a million years. I'm astounded at how you solved it.
@snakeyesz
4 жыл бұрын
That's incredible what you found because your first number was my last to mark down this was the first time I've tired marking everything down I see and did not know what to do, then i saw just one pair and that was in column 8 236, 236,6 then I placed the 6 in and then after that I kept placing more and more numbers that didn't not line up with my pencil marks but I kept going with what I put down also at the same time doubting it and THINKING I'm eventually going to mess-up but it did not happen. This for me was beautiful and at the same time puzzling thanks Simon!
@MrEvenStranger
4 жыл бұрын
13:48 - I think I lucked into it. Once the fives fell in place I could compare columns, rows and squares to eliminate numbers and place digits.
@policarpo4816
5 жыл бұрын
Wow. This puzzle was truly incredible and surely the best I’ve ever seen. Also, congratulations for solving this diabolical sudoku. I had my mind blown. 👏🏻🤯
@rabidsamfan
5 жыл бұрын
I love how many different ways people approached this!
@ManfredoStagnoGD
4 жыл бұрын
Yes, that is the best sudoku of all-time! What a puzzle!
@CraigSoupen
2 жыл бұрын
I found the 1 in row 3 by using the symmetrical counterpart 9.
@eshosora9339
3 жыл бұрын
(5) in center= result of four times (x wing) intersection of number (5) arround.
@cindyshirey8561
2 жыл бұрын
LOVE THIS ONE !
@cmonkey63
5 жыл бұрын
I had a dream like this once. One day for dinner we had a lamb roast with way too much garlic, and I spent the night dreaming in feverish logical structures. Unlike my dreams, this puzzle did have an exit. So glad.
@Zuzurp
5 жыл бұрын
It took me a while to figure it out, but here's another way to solve it based on the 90-degree symmetry: A 5 in R2C3 would force a 9 in R2C4 and, by symmetry, a 5 in R3C8. The 9 in R2C4 brings a 1 in R8C6, leaving the 6 as the only option in R3C6. It also forces a 9 in R1C9 The 6 in R3C6, by symmetry (clockwise: 3>4>7>6 and 1>8>9>2), brings a 3 in R6C7, breaking the puzzle as there is no spot left for the 3 in the top-right box. Thus R2C3 is a 7 and everything just unfolds from there. If I didn't get anything wrong...
@045tom
2 жыл бұрын
is there a way to play a sudoku with this software at an easy to medium difficulty?
@bfish89ryuhayabusa
5 жыл бұрын
I find it odd that you only treat the rotational symmetry as 180° and never 90°. They all link together, 3-4-7-6 and 1-8-9-2. Solving any one immediately gives you the other three. (and each 5 gives you three other 5s)
@bfish89ryuhayabusa
5 жыл бұрын
I'd be curious if you could just solve one quarter of this (columns 1-4, rows 5-9, for instance), as that would give you the rest.
@julieannmyers8714
3 жыл бұрын
11:07 but spotted nothing about 3467 or rotational symmetry! I'm an inveterate plodder.
@nigelm5777
5 жыл бұрын
Sudokuwiki.org graded this gentle/easy and the first four steps were to run through x-wings on 3,4,6,7. From there just simple steps. Of course all candidates had first to be filled in. The genius is to get all that from symmetry. Beyond me! Interestingly the central 5 was found in the last few steps.
@Jr8key
7 ай бұрын
I found 2 bent triples and solved it that way
@alexbove106
5 жыл бұрын
I'm almost ashamed to admit it, but I used Mark's bifurcation method on the bottom-right square in the bottom-left cell and it completely cracked the puzzle.
@CrackingTheCryptic
5 жыл бұрын
Don't feel ashamed, that's exactly how Mark solved it too!!!! I told him I thought the puzzle was absolutely incredible and he had no idea what I was talking about.
@woodchuk1
4 жыл бұрын
4 X-wings 4 W-wings 1 Hidden Quad Took about 30 minutes...not a terribly difficult puzzle, but a decent challenge.
@FloydTaylor
3 жыл бұрын
WOW four x wings forcing quads
@slashbin_fr
4 жыл бұрын
i've completely lost you at the beginning, too hard for me
@dbass4973
4 жыл бұрын
somehow solved it in 17:45 without noticing any symmetry and/or x-wings
@normanndaba8823
3 жыл бұрын
This is sorcery 🙈
@ManishKumar-ks8ou
4 жыл бұрын
I solved this Sudoku without using any technique... Just with error and trail method
@04LightningFan
5 жыл бұрын
Simon, finding that 3467 quadruple using the x wings was absolutely brilliant.
@eternalblasphemy6526
3 жыл бұрын
Honestly, all you need is to find a swordfish on 3s and x-wing on 4s to break the puzzle. Funny enough, I tried to solve it a year ago using symmetry and got stuck (thankfully, was able to solve it the stadard way).
@Penguincw2
3 жыл бұрын
Anyone here after Simon mentioning it in today's vid?
@stereomike75
3 жыл бұрын
What's the first thing that jumps out to you watching this vid? Simon's voice! It's like listening to his brother, it's so weird.
@Penguincw2
3 жыл бұрын
@@stereomike75 Definitely the change in setup: his camera is further away and he sounds different.
@simonplanting5948
3 жыл бұрын
Yes, hadn’t seen this one before... relatively new to this great channel...
@nicksm7980
3 жыл бұрын
His haircut is ok though.
@awilliams1701
3 жыл бұрын
I meant to, but I didn't have time and then I forgot so here I am 5 days later. lol
@RandomBurfness
5 жыл бұрын
Something you didn't notice about this puzzle is the rotational counterparts are the pairs that add up to 10. You have 1 + 9 = 10, 2 + 8 = 10, 3 + 7 = 10, and 4 + 6 = 10. No wonder there was a lack of 5's in the starting grid, those only pair up with themselves to make 10!
@Wecoc1
5 жыл бұрын
The numbers could be swapped and you would still have a valid solution, that 10 sum property was probably made just to make it a bit easier to remember the correct pairs.
@PeterJavi
5 жыл бұрын
@@Wecoc1 Given the 1-9 property of sudokus, it's quite natural to pair numbers that way, especially if you want that extra layer of symmetry.
@Chroniknight
5 жыл бұрын
That's cool! I didn't notice that
@sunriselg
4 жыл бұрын
The best part for me about that is the way I do notation: I divide each cell into a 3x3 grid and colour in everything it can't be. That way even the numbers are rotationally symmetrical and so is the solution of this puzzle.
@JohnRandomness105
2 жыл бұрын
There was a more complicated 90-deg rotational symmetry. Rotate 1-2-9-8 and back to 1. Similar for 3-4-7-6.
@Augmentfluup
5 жыл бұрын
I'm sure this has been mentioned before, but please, don't spoil the solve in the thumbnail. For example this video spoils an X-wing
@shane8037
5 жыл бұрын
At least you don't know what the number is for this one. Sometimes half the board is filled in on the thumbnail!
@soundcrank6214
4 жыл бұрын
@@shane8037thumbnails are tiny, stop studying them so intensely
@sunriselg
4 жыл бұрын
I did not pay attention to the thumbnail, but your comment spoiled it for me. I think I would not have been able to solve it without that hint.
@alexortiz9777
4 жыл бұрын
@@sunriselg dont read the comments on a puzzle before solving it!
@brendabalzan1994
4 жыл бұрын
I solved it without realizing there was X Wings. I saw something on the thumbnail but I still am not sure how to do them.
@Pyromonkey83
5 жыл бұрын
Absolutely breathtaking. This is one of those puzzles where I wish I had more friends interested in Sudoku, because this is just immensely satisfying to solve. It is 100% buildup of compounding logic to an absolutely stellar collapse. I did not know about the Gurth's placement rule, so the 5 in the center was actually the last digit that I placed, but it took me nearly a full hour to get there. I spotted the X Wings rather quickly, and loved going around the grid with them, but it wasn't until much later that I realized how profound of an effect those digits had on the middle edge pieces to give an astonishing hidden quintuple, followed by the hidden singles in the inside corners of the middle edge boxes. This is, without a doubt, the best puzzle ever featured on this channel, and I absolutely love it.
@AWildBard
4 жыл бұрын
I was wondering if it could be solved without knowing the 5 would be in the center, because I wouldn't be able to recognize that.
@NelielSugiura
5 жыл бұрын
Once I saw it is just a pinwheel rotational symmetry, I applied that theorem from another video of yours and knocked out the puzzle in about fifteen minutes. This would have been a great way to introduce that theorem, too, and show that it applies not only to two directions (like a mirror or 180), but also to four (90 degrees). I feel you touched on this at the start with your mention of the "animal" shape being rotated around, but you had not noticed all the numbers rotate, too. It would have made it way faster and is a lot more creative/clever when you see that!
@KJGrenadier
Жыл бұрын
You mind linking the video that has them using the pinwheel rotational symmetry? I would love to learn about it. No worries if you cannot; it may be hard to find (unless it is in the title?).
@sunriselg
4 жыл бұрын
About Gurth's symmetrical placement: If the start is symmetrical, the solution must either be symmetrical or ambiguous: Suppose there was a solution that isn't symmetrical, then rotating that solution by 180 degrees and transforming the numbers according to the symmetry would also be a solution to the same initial state.
@asmodeojung
4 жыл бұрын
That's a nice and easy to understand explanation.
@yichen6313
4 жыл бұрын
Interesting. So it's essentially invoking uniqueness.
@draconicdusk5911
5 жыл бұрын
So, I spotted something. We can use uniqueness to crack this puzzle wide open. in the 5th box you have: 128 in square 2, 129 in square 4, 189 in square 6 and 289 in square 8. Now the thing is, what I spotted was that we would most likely have to solve the puzzle by placing any number that isn't a 5. If we were to assume that square 4 and 6 of box 5 were a 19 pair, we would hit a problem. The puzzle would have 2 solutions, because the 19 would be semetrical either way. Thus I ruled out the 19 from square 4 and 6 in box 5 leaving a 2 in square 4 and an 8 in sqaure 6, this left a 1 in sqaure 2 and a 9 in square 8. from there, the puzzle is easy. Took me 4 minutes after the Gurth's symetry was mentioned.
@Desslosh
4 жыл бұрын
I spent about one hour filling this sudoku with notations, only being able to place the 5 in the center. Only after a long time it dawned upon me one of the first digits you placed, and then the puzzle solved itself. Completely amazing.
@ChessRabbitt
5 жыл бұрын
Wow! I am doing this puzzle again and I can't get one number.???? 20 mins in so far. Why is that I wonder? Signed confused
@f.b.jeffers0n
Жыл бұрын
In the future, you solve WAY more interesting puzzles, fwiw...
@abubakardouglas8268
5 жыл бұрын
It totally stumped me. I saw the symmetry but had no idea what to do with it. Great puzzle
@JqlGirl
4 жыл бұрын
I found the unwinding a different way. Once I had all four xwings marked, I noticed that they forced their opposite digit into the middle, and since each middle two had to contain both an xwing number and the number forced in by the xwing, they couldn't contain any other digits. Same result, but different logic without finding the double 3467 quad itself.
@jrpstonecarver
4 жыл бұрын
Woah. First time I have ever solved one of these on the first try, and without the video. 28:33. And I didn't use the X-wing technique. Great puzzle!
@r0bw00d
4 жыл бұрын
I'm not nearly good enough to tackle this level of challenge. I spent 45 minutes just with the pencil marks and, although I spotted the spiral pattern, I didn't know what to do with it.
@johnnull1375
5 жыл бұрын
commenting before watching past the x-wing discovery, I needed that help to get going! there is also a quarter turn symmetry as well, 2 to 1 to 8 to 9 and 3 to 4 to 7 to 6; so any time you get one number, you actually get 4 ! simply amazing!
@notavan17
5 жыл бұрын
Very interesting! Once I finished Snyder notation, found pairs in rows and columns 2 and 7. Then looked at 4s and followed a logic chain that placed a 4 in r3c1. Then the rest pretty much fell apart. Took 15:17 for me. It's cool watching your methods after I finished my solve.
@Djsrox96
5 жыл бұрын
Did the same thing and got it in 16:17
@wazzzuuupkiwi
4 жыл бұрын
this was an amazing solve, it took me 54 minutes :P and I didn't know the pairs trick. what I used was filling in all 50-50's in all rows columns and squares, found 3 x-wings that way, then still had no digits to place. but 1 of the pairs linked 2 xwings, so I decided to see how many digits I could cascade if I pick one of the pair. then the same for the other option. this gave me the center 5 and nothing else until I used the x-wing property to give me 1 more 50-50 inside the top middle square, that led to a break in one of the 50-50's cascade causing me to pick the other one and fill it all in. after that so many digits were filled in that basic row/column checking solved the rest. VERY satisfying!
@pimo01
4 жыл бұрын
I am positively thrilled at the moment, it usually takes me more than a solid hour to crack the sudokus posted here but today I was just past the 30' mark when I discovered the symetrical solution. The thing is after that I didn't need any x-wing strategies because after placing the initial central 5 I noticed that, 8 and 2s as well as 9 and 1s were positionned in the same manners throughout the grid, one obliquely to the other and I dive into that and started placing the 8,2,1,9 that I could using that visual way of placement, which has no sudoku logic to it I have to say, it then took me another 15 minutes with traditional sudoku technique then to finish, really marveling at the genius behind this grid with each added digit. I'm so proud of myself there, I'mnot usually the boasting type, but really glad all the same. Thanks a lot for posting that wonderful game.
@echoes6092
5 жыл бұрын
Wow, that was an amaazing solve!
@Blubb5000
4 жыл бұрын
I managed to crack it by finding quads in row 5 and column 5, which ruled out a lot of candidates. From there on it was a breeze.
@jamesyoung1022
4 жыл бұрын
Once you got me looking at the symmetry, I solved it by figuring out the symmetry alone. Looked for patterns of odd and even digits. Didn't use any x-wings.
@tadperry1817
4 жыл бұрын
Okay, very interesting regarding me and this video. At the time I write, I've been watching the videos for about 3 weeks only because I found them interesting, and started trying them about a week ago, because I though "I want to be able to do what Simon does.. As usual, I started it on my own and put in all the pencil marks using Snyder notation and then continuing with the intention of starting the video if/when I got stuck. I had absolutely exhausted all Snyder pencil marks and I was certain of their accuracy. I didn't know about the implications of the symmetry and I didn't have a 5 in the center. This approach had not produced a single "normal" entry. I hadn't noticed that the numbers themselves had been paired up. So I did what Simon always suggests at that point and looked for the most highly restricted squares and found the 57 and 59 pairs in row three by process of elimination. I kept going forward. In fact, I found the 56 and 25 pairs in column 8 as well as the 35 and 15 pairs in row 8. At this point, I was worried that I was making my usual logical errors and wanted to watch the video just to see if Simon was doing this the same way or had a better method. I was absolutely gob-smacked to see what he did to get all the same information! He abandoned continuing with Snyder and switched to using the symmetry in the grid!! At least I was happy to find that I hadn't made any mistakes and turned the video off when he found the last 45 and 58 pairs in column 2. At that point I stopped the video and went back to trying to solve it on my own.
@tadperry1817
4 жыл бұрын
57 and 59 in row 2.
@allanlindjensen2306
7 ай бұрын
There is a stronger symmetry: Rotating 90 degrees to the left maps 1 -> 2 -> 9 ->8 -> 1 and 3 -> 6 -> 7 -> 4 -> 3, and then 5 -> 5. Is there a way to weaponize that observation?
@JohnRandomness105
2 жыл бұрын
2:00 The puzzle appears symmetric under 180-deg rotations and substitutions of N and 10-N. (Later) I always need a comment or phrase, to clue me into something potentially cracking the puzzle. I'd already found two X-wings, but a comment just under mine alerted me to two more X-wings. (Later still) The comment led me to search for and find not one but two 3467 quads. There was a 90-deg symmetry. And I solved the puzzle. 4:50 The symmetric placement theorem: I think there are two versions. 1st involves placement. If your placement doesn't follow the symmetry, then you've omitted possible placements. So if you place 1 into the central cell, 9 is a candidate by 180-deg rotation. Then by 90-deg rotation, 2 and 8 are also candidates. The 2nd version of the theorem is that the solution is itself symmetric under the transformations. This version assumes uniqueness, which one should probably avoid. One would rather prove the existence of a unique solution, by solving the puzzle. If the solution is unique, the central cell must be a 5, and 5s elsewhere must remain 5s under 90-degree rotations. But if the solution isn't unique, the central cell could be another digit. 9:20 "I'm sure most of you are familiar with sevens." I was reminded of a hypnotic trick where subjects are made to forget the number seven.
@joopjansen9102
3 жыл бұрын
I was not sure about that central 5, so I decided to ignore that as a given as long as possible. With the (brilliantly found!) 3467 quad, the puzzle can be finished without that central 5. What I took from your explanation is the symmetrical bit - not as a rule, but more as a clue to find the x-wings. I had found the 6 wing and found the 4 wing on your hint. The 7 and 3 wings proved to be very powerful as well, but not as powerful as your 3467 quad. I'm slowly getting better at finding x-wings and their implications - I'm just a noob, using pairs, triples and quads to find the singles. Hope to climb to the next level (wings, swordfish, empty rectrangles) soon. Any suggestions anyone on how to proceed? Thanks for the lesson Simon! A joy, as always!
@paulwatson746
4 жыл бұрын
My best "Hard solve" - spot the 4 way rotational symmetries, 9-2-1-8 and 3-4-7-6, get a couple more centre groupings, soon leads to , 1 in row 2 cell 6 (using bifurcation (guess)) (this took 20-25 mins) - and everything else follows. No need for X wings at all just follow the 90 degree rotations and nice doublets miraculously appear. 29 mins totals with also having to re track from an error.
@ScorpioPK
3 жыл бұрын
It took me almost 3 hours to solve and I was getting frustrated that I knew the middle had to be a 5 (instinct, I guess), but I couldn't prove it. After 2 hours I managed to eliminate 5 from the middle line/column of each outer cell leaving the 5 in the middle. And you just did that in the first minute because of a rule I never heard about. I guess I basically proved it :))) Then, it took me another 30 minutes to spot the quadruples (1289) and then it collapsed. I am usually no good at finding X-Wings or other techniques (I am new to sudoku), but I did find 4 X-Wings and 4 Y Wings in this puzzle, which didn't really help that much. Beautiful puzzle!
@ericl2811
5 жыл бұрын
So a few things. First, this is the first puzzle from the title alone u finally decided to try it myself with your program. (I thought it would bring me to an app, which is why I've put it off this long.) And I love that it automatically brings it up without downloading anything! Thank you so much! Second, since this WAS the first puzzle I tried before watching the video I saw the multiple X wings and the symmetry but I got completely stumped and couldn't make any progress pass that! After over an hour I finally gave up and started watching the video!
@vincentcarrocci4697
4 жыл бұрын
Someone please correct me if I'm wrong on this: Once a 1 was able to be placed in Row 3, Column 6, the next move by basic Row/Column Sudoku logic would be to place the 5 from the 1-5 pair in Row 8 Column 6. From that point, the puzzle unlocks without using any symmetry or advanced techniques.
@christiancoester2455
3 жыл бұрын
Amazingly, there is not only a 180-degree rotational symmetry where x maps to 10-x, but also rotation by 90 degrees always maps the digit x to f(x) for a fixed function f (e.g. 1 always maps to 2 when rotated by 90 degrees counter-clockwise).
@philipmetcalfe4736
2 жыл бұрын
My first ever solve of these type of puzzels that Simon or Mark solve...but to be honest it was the 5 that Simon said had to go in the middle square and know where else that set me up after I had done all the notations that could be put in...I could see a sort of pattern..but did not know how it worked....i just followed my nose and et voila....solved...but not like Simon...I had a hunch that the corner numbers were the single digits that did not have a match in the next square...i,e top left square R1 C1 =6, top right square C9 R1 =3 bottom left C1 R9 =7 and bottom right square C9 R9=4...
@insaneyankee4996
3 жыл бұрын
This one doesn't have to be so complicated.When you found X wing of 7 in C2 and C7 with the help of that we can easily find swordfish in R2,R3,R4 .This Xwing and Swordfish will give us a '7' in R9C1 and then puzzle will fall apart.
@JXPLennox
3 жыл бұрын
I was able to solve it without any advanced techniques, no conclusions from symmetry or x-wings. The 5 in the middle was the fifth to last field that I filled in. It took me 27:28.
@ol1ver49
4 жыл бұрын
I solved this quite easily by makingg an assumption about how the 1,2.8 and 9 were placed in the central square. (1 and 9 vertically, 2 and 8 horizontal). I think my assumption was justified by the symmetry rule but so far I can't prove it.
@MotoCat91
4 жыл бұрын
Rather than spotting the 180 degree symmetry, I actually found a 90 degree pattern instead, with the same ultimate conclusion but makes a few placements a bit easier. So working counter clockwise, 1 -> 2 -> 9 -> 8 and back on itself 3 -> 6 -> 7 -> 4 and of course 5 -> 5 So when one number gets placed, instead of only showing it's opposite counterpart it also filled in the other 2 automatically. I got the original centre 5 within the first 10 mins, but then I was at 1hr20 before I spotted that 1 as the second placement. From there it all collapsed in under 3 mins. Finding that second digit was truly evil, but it's such a well made puzzle
@rickroll9086
4 жыл бұрын
Yikes. Was able to do it after the 3467 x wings were pointed out, effectively forcing the 1 into R3C6. Don’t have to use symmetry (the center 5 was one of the last to be filled using basic elimination), IF could have found all 4 of those x wings (which I didn’t on first go), but it seemed to help Simon spot the wings in the first place. After that, not really required to solve. Placing that first digit was a beast; kudos.
@The_Cali_Dude_88
5 ай бұрын
Due to its rotation notice, your inner block numbers 3, 4, 6 & 7 end up at the edge of the entire puzzle corners at the end. Additive numbers surrounding the 5 end up in their respective center points on the outside s edge as if the central block of the cube just 'blew' up and a puzzle was created ✨️
@michaelkolb4344
3 жыл бұрын
Okay, I know, after more then a year after publishing this video, there might be no point in dropping a comment, but... I wonder (or I'm not sure), if the solution to this sudoku is truly based on pure (sudoku) logic. I didn't recognize (or bothered with) the symmetry, but I spotted the four x-wings. But they weren't very helpful without the 5 in the center and I was not able to put it there, based on pure (sudoku) logic. In my opinion the two 3467 quadrouple only work with the assumption (or the educated guess, based on experience), that, due to the symmetry of the puzzle, there is a 5 in the center.
@Keyboardje
3 жыл бұрын
18m 28s :o I'm astounded I solved this one, but I guess because of being Dutch it made me think of the wings of a windmill. That's how I spotted the symmetry, and by that the x-wings :) Edit: But it turns out I did the solving slightly different than Simon.
@theAng3r
4 жыл бұрын
once you discover the x-wings if you had looked at R9C5 you find it can only be an 8. and the with R1C5, R5C1 and R5C9 all down to 2 digits the whole puzzle just falls apart.
@G.Aaron.Fisher
5 жыл бұрын
After spotting the symmetry, the 5 made total sense to me and I was able to fill it in. I didn't see the X-wings at all. However, this puzzle folds quickly to bifurcation if you make good use of symmetry. Bearing symmetry in mind, there are really only 14 unknown cells in the puzzle, rather than 57. That leaves very little typical sudoku work. Kind of like a 2x2x2 Rubik's cube, it can be solved just by playing around with it a bit.
@Zuzurp
5 жыл бұрын
There is actually a 90-degree rotational symmetry (3>4>7>6 and 1>8>9>2). But so far I am failing to see if it could help solve it a bit more easily.
@richardhenrysutterrosendo3439
4 жыл бұрын
Thanks! I was looking for this in the comments, to see if more people noticed it too. Indeed, the best puzzle already presented here.
@richardhenrysutterrosendo3439
4 жыл бұрын
Also, this helps by forbidding 5 along the main diagonals (except from the central cell). But I was not able to use this fact further.
@chrisengland5523
3 жыл бұрын
That's the most weird Sudoku I've ever seen. I managed to solve it before watching the video, albeit not in the time that Simon did it in. I used the symmetry and the X-wings, but then did the rest in a different way. The 4 initial X-wings eliminated digits from several squares, which led to what looked like 4 more X-wings, but in each case, one of the 4 corners was blocked (seen by another identical digit), so these 3-legged X-wings immediately gave me the pairs of digits and then the puzzle fell apart. (To be fair, I had already seen Simon's other video on Gurth's Symmetrical Placement, which gave me a big starting advantage.) Watching Simon go through the same steps and discovering the X-wings was really funny. Simon struggled with the notation at one point and used central pencil numbers to annotate the X-wings. I had an advantage here, being an electronic engineer, I am familiar with the resistor colour codes. Each digit 0 - 9 is represented by a different colour and whilst the colours available don't quite match the required colours, I was able to identify the X-wings by colouring them with the relevant resistor colour code colour. That helped a lot. It would be useful to be able to use red pencil numbers to indicate where a number is NOT possible. That would be far cleaner than listing all the other numbers and missing out the impossible ones.
@ol1ver49
4 жыл бұрын
Astonishing. I got as far as you but couldn't find that first X-wing, so I cheated and looked at the video. Once I saw that I knew there'd be 3 more - same when you got that first digit in (the 1) I knew I'd find 3 more. After that I solved it with a different routine to you, but probably logically equivalent.
@georgesthibaudeau1533
2 жыл бұрын
This was brilliant solving. I was not alert enopugh to see those X Wings. What I did is completely different. After entering the snyder notations as you did, and spinninf my wheels for eons, I noted the particular interactions of the 3 and 7 in that rotational symetry. In box 4, we had a 9 in two positions in the lower rows of c1, with the counterpart in box 6 being the 1s in either of the upper rows of c9. Back in box 4, the 3s were either ia pair with the 9s or in r5c3; symetrically in box 6, the 7s were a pair with the 1s or in r5c7. Now when you take a good look at that, you cannot help but see that the flow of rotation requires the 3s to be a pair with the 9s in c1 and vice versa for the 7s with the 1s in c 9. This may have been somewhat instinctive, but it worked marvels, so much so that after a very painful beginning, I finished the puzzle as if it were sudoku 101.
@AnaheimBN
3 жыл бұрын
That's a brilliant thing to use this kind of logic. But seems like you did that in purpose because it could have been solved by basic techniques in half and rest by symmetry :)
@Deafingblow
5 жыл бұрын
What a fantastic puzzle took me just under 12 minutes to solve! edit: for anyone wondering, I first filled in every possible number, except for 5's, then looked where a 5 could and could not fit into the grid. imgur.com/a/CmfrYkO
@russellsharpe288
Жыл бұрын
Hilarious. Having noticed the rotational symmetry and the summing to 10, I felt sure the centre square must be a 5 and then just 'guessed' the rest of the interior 3x3 square (as it turned out, correctly). Then it all fell out in a few minutes. Not remotely rigorous, but it worked.
@kaffemulen
3 жыл бұрын
Was I the only one solving this using Phistomefel's ring? That was according to me by far easier than Simons version (I’m not a very advanced solver, at all, and still I was clocking in at just above 21 minutes).
@solfeinberg437
2 жыл бұрын
Gurth's symmetrical theorem. The placement and the values of the starting grid are symmetrical around the 180 degree rotation. Seems like this would automatically mean the full solution would have the same symmetry. (Or there would be some symmetric ambiguity.)
@pilotandy_com
5 жыл бұрын
It took me 10 minutes just to figure out it was symmetrical.
@DamianFloresRF
4 жыл бұрын
I'm impressed by how quickly you solved it. I did it in about three hours. It took me a lot longer to be absolutely sure that it was ok to assume that I had to put a 5 in the middle despite not being able to prove it with common sudoku logic. After that, I solved it in a very different order. There are several steps you made that I missed, so my method was messy, but entertaining: I made a "wheel" with 2, 1, 8 and 9 and put them in the middle quadrant. I tried the three possible rotations (the fourth was blocked), looking for inconsistencies. Two failed. The third was the charm. Even if I had got it right in the first one, I would have later tried the others to check.
@geraldsmith7401
3 жыл бұрын
Hi: I don't know much about x wings etc. All I did was substitute a 4 in the second column above the 2 and 9. There could only be a 4 or 5, so I got lucky and picked the right one. In doing so, It took me 21 minutes and 8 seconds. Lucky me. Thanks and keep up the lessons.
@tinakerr8163
2 жыл бұрын
Instead of pencil marking the x wings on 3467 which is confusing, I found it helpful just to use a colour to mark the different x wings and colour the corresponding digit in the central square, a bit using a legend on a map.
@kgeiger61
4 жыл бұрын
Once I noticed that it was 180º rotational symmetrical, it fell like dominoes. Solved it in 14 minutes.
@lrvogt1257
Жыл бұрын
I did it the hard way by filling in color to determine everywhere there were two matches in a row. I had nearly every such hint for every number and still didn't have a single digit filled in until I found a 6 and then the whole thing unraveled like a cheap sweater. :-)
@timdunkley9173
4 жыл бұрын
Remarkable puzzle. The symmetry aspect actually being a red herring made it even more impressive. Standard corner and centre notation on its own reveals the four X wings. Then the hidden quadruple is pure genius.
@Pwecko
3 жыл бұрын
I managed it in 29:50. However, I did have to resort to a tiny bit of bifurcation, as I didn't see the rotational pattern. Cheating, I know.
@SawyerAndGretch
3 жыл бұрын
Learned a lot from this video. Saw the symmetry, but did not think about the x-wings.
@tessjuel
5 жыл бұрын
That's an absolutely amazing puzzle, thank you for posting it! The only problem, I tried to do a regular sudoku afterwards and struggled because I kept lookign for the symmetry that wasn't there. ;-)
@ChessRabbitt
5 жыл бұрын
I would like to thank you all for this channel. Six months ago I would not be able to solve this, or any hard puzzle, at all, let along in less 30 mins. Thanks you for making me a better Sudoku solver.
@xxpatrick204xx
4 жыл бұрын
Not the perfect sudoku in my opinion because it's faster/easier to solve by guessing any box that has 2 options
@kradoyen4929
3 жыл бұрын
A new PB for me! 17:20 without watching the video first time I have a time below 30, can't believe it
@insectbah
3 жыл бұрын
23:52, but not particularly elegantly done by me (two x-wings though)
@senixahaa
4 жыл бұрын
I did this in 16m without noticing the symmetry. I feel as if noticing that and explaining made it take longer than not noticing.
@Kuraudo_VII
4 жыл бұрын
This one is seriously beautiful. The total spiral symmetry is amazing. I would love to see more of this kind in the future. And this is probably the first one where I solved it with close to exact number of minutes you used.
@stuartw969
5 жыл бұрын
Unbelievable! Congratulations! You kept calm and mastered the most difficult of puzzles.
@angelalbericoninojimenez1884
3 жыл бұрын
Increible este Sudoku, que lastima que no este en español, no es igual leer los subtitulos, sin embargo se aprende mucho. Voy a tratar de solucionar este sudoku por mi cuenta a ver que tal me va.
@gerryandlizkeogh1817
5 жыл бұрын
Even after watching it solved I don't understand it! Sheer brilliance in setting and solving well done!
@BLACKATELIER
2 жыл бұрын
just completed in 8min 22 while listening along, great puzzle
@yichen6313
4 жыл бұрын
Wow, beautiful! I didn't use any rotational symmetry arguments since I was not sure if it's guaranteed that the initial numbers are rotationally symmetric that the final solution is also rotationally symmetric, though in this case, it turns out to be true. (Time to look up some proofs) What did it for me is the bent quadruplets in for example r8c6 + r3c6, r3c8, r3c9, which allows me to erase some pencil marks in c6. Similarly for the few other places on the board. Then some quintuplets appear in r5 and c5. Then it breaks open.
@yichen6313
4 жыл бұрын
Hmm the Gurth's argument is essentially a uniqueness argument. Not a big fan of using it...
@Chroniknight
5 жыл бұрын
This took me 45:07 (attempted before watching), however I'm just surprised I got it
@jbsoul4575
4 жыл бұрын
Good job, I gave up in about 5 min.
@PattyManatty
5 жыл бұрын
Is there a proof of gurth's symmetrical placement? It doesn't seem at all obvious to me that just because the givens are symmetrically placed, that the whole grid is symmetrically placed
@thanderhop1489
5 жыл бұрын
I think a heuristic proof is as follows. Suppose the grid is symmetrically placed to start. Now suppose you use logic to determine a digit. Then symmetrical logic will also determine the digit in the symmetrical position. Thus, the puzzle is still symmetrically placed. Thus, the puzzle will never not be symmetrically placed throughout the process of solving, so it must be symmetrically placed when it is completely solved.
@cablebee8790
5 жыл бұрын
It’s not just the shape that’s symmetrical it’s the specific digits
@stegra5960
3 жыл бұрын
Took me 6 hours 18 minutes! Got my first digit 5 mins from the end.
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