Another Sudoku Breakthrough: Man Vs Machine

Рет қаралды 57,956

2 жыл бұрын

Our series of videos showcasing brand new sudoku techniques continues with noXing by Qinlux. The computer can't make head nor tail of this one and has to resort to an esoteric series of guesses. But this puzzle is absolutely solvable by human beings - indeed it has a beautiful trick. Give it a try at the following link:
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Пікірлер: 231

@HunterJE 2 жыл бұрын

"I got this digit without doing anything complicated!" Yes, definitely nothing complicated in those overlapping finned X-wings.

@khayman9574 2 жыл бұрын

Same feeling here 😅

@itsmeagain1745 2 жыл бұрын

AND he happened to find the neede 1,2 in the centre cell of box 5.

@RyanAtOptimism 2 жыл бұрын

HAH! Yes!

@leppyr64 2 жыл бұрын

@@itsmeagain1745 To be fair the 12 in R5C5 is very visible after finding the two finned x-wings.

@BillGatliff 2 жыл бұрын

I did a spit-take myself when he said that. 😂 Though, to be honest, he makes it SEEM easy.

@thealienontheinternet 2 жыл бұрын

22:44 “I got this digit, and I got this digit without doing anything complicated” said Simon after finding two overlapping finned x-wings that are symmetrical along the positive diagonal

@iabervon 2 жыл бұрын

I think what he means is that the standard technique produces an inference of the form "if r1c9 isn't 2, r5c5 isn't 2", and if you can remember and use that statement when you find the same thing for 1, it's obvious that the pencil-marked 9 leads to a contradiction. The key statements are simple bits of human logic, but they're not things you can standardly mark in a sudoku grid.

@angelmendez-rivera351 Жыл бұрын

@@iabervon Eh. If you have actual paper, pencil, and an eraser, then marking such things is pretty trivial.

@HierarchyHD 2 жыл бұрын

As a software engineer, it’s so interesting to see a puzzle that stumps the computer into bifurcation, yet is so elegantly solved by a human. Always a joy to see an upload 🙂

@bluerizlagirl 2 жыл бұрын

It's about known patterns. If you can recognise a definite pattern such as an X-wing or swordfish, there are some eliminations you can make straight away. If you do not recognise the pattern, you will still be able to get it from first principles by following chains of either-or possibilities and seeing if anything is the same either way.

@ccash3290 2 жыл бұрын

A computer program is just someone in the past solving the problem

@bluerizlagirl 2 жыл бұрын

@@ccash3290 Yes, exactly! Somebody found a pattern and worked out the more general form of it, which they then expressed in a programming language.

@bobbobson6867 2 жыл бұрын

@@ccash3290 You can make computer programs that discover new patterns and new ways to solve. But it is much harder to create such programs!

@thegolddog5583 2 жыл бұрын

The computer didn't bifurcate. It looked more deeply than we can but just followed logic without branching.

@inspiringsand123 2 жыл бұрын

Rules: 05:45 Let's get cracking: 05:54 And how about this video's Simarkisms?! Beautiful: 6 (22:52, 22:54, 23:32, 24:13, 30:22, 31:20) Good Grief: 4 (25:00, 27:17, 29:33, 30:25) The Answer is: 3 (18:05, 20:08, 23:29) Maverick: 3 (04:05, 04:05, 10:55) Elegant: 3 (02:07, 03:26, 25:59, 30:47) By sudoku: 3 (29:02, 29:06, 29:08) Bobbins: 2 (27:46, 29:47) Sorry: 2 (03:44, 20:27) Extraordinary: 2 (03:48, 04:39) Our old Friend Sudoku: 2 (26:43, 30:04) What on Earth: 1 (02:09) Useless: 1 (20:27) Naked Single: 1 (09:34) Chocolate Teapot: 1 (20:22) Clever: 1 (25:21) Lovely: 1 (29:58) Incredible: 1 (05:21) Take a Bow: 1 (30:25) FAQ: Q1: What is a Simarkism? A1: A Simarkism is something that Simon and Mark typically or frequently say. Q2: How do you do this so fast? A2: I'm not made of flesh and blood, but of sand ... Q3: Why don't you include 'XX' and 'YY'? A3: Probably it's already on the list ('Scooby-Doo' for example), but not mentioned in this video. But if you think it's not, tell me what you'd like me to include and there's a good chance I'll add it! Q4: You missed 'XX' at 'YY:ZZ'! A4: That could very well be the case! Human speech is hard to understand for computers like me, especially British sometimes! Point out the ones that I missed and maybe I'll learn! Q5: Could you turn these statistics into videos? A5: I've been playing around with the idea and I'm open to input as to what people would like to see. Let me know if you are interested in this and/or have suggestions.

@Turidus 2 жыл бұрын

Amazing Work!

@RADZIO895 2 жыл бұрын

The amount of "beautiful"s after simon found the tech lol

@alexhypnosis 2 жыл бұрын

I want to give this comment 100 likes. Please keep up this valiant work.

@drewmanzara5731 2 жыл бұрын

Why don’t you include “unfairly maligned”

@Anione111 2 жыл бұрын

A true fan 😄!!

@dalewier9735 2 жыл бұрын

Simon, at 24:16 i “saw” what you were saying (after a pause of about 10:00 minutes). You have my subscription and my thanks. I have loved sudoku for years but after 25 days of fever from CoVid last month, (and very nearly expiring) I have had a bit of “fog” concerning logic and memory. I have been watching as a tonic of sorts. So not only are you a wonderful solver and teacher but your method of speaking the logic you are using as you work is therapeutic.Thank you. Stay healthy. Blessings to you.

@Anione111 2 жыл бұрын

Don't beat yourself up. Most of us suffer from the brain fog without even contracting Covid 😁. Just imagine, you beat the virus, if you ask me, that's better than solving the most cryptic sudoku!

@cypher686 2 жыл бұрын

Hope you got a vaccine and aren’t one of these anti-Vaxxer douchebags

@1fosters 2 жыл бұрын

The simple elegance of using digits 1 & 2, rows and columns 1 & 9, the corner, and the centre cell. Letting the idea speak for itself rather than hiding it further.

@jovi_al 2 жыл бұрын

This puzzle has got to be in my top 10 of favorite classic Sudokus ever! I solved this right when it came out and am just in love with it.

@michaelbaker9347 2 жыл бұрын

That's some high praise from such a brilliant constructor yourself!

@FireSiku 2 жыл бұрын

Wow, after I heard this was another one of those "Throw it in a computer" puzzles, I immediately jumped into geometry tricks, and while Phistomefel's didnt return anything useful, I found the outer edge a lot more cluttered than the rest. So I did the variant that takes the four corners + the outer ring that Simon used in various other videos and found that 15 of the 16 digits were already given. I kinda expected that wouldve been Simon's break-in as well. Then, the even more surprising thing: The remaining cells that needed to be discovered in the outer edge formed an odd swordfish pattern. The missing cell that would "complete" the pattern was the 12 in the middle. That discovery led to realizing the corner cell had to be 1 or 2 because both were already found in the inner region. It truly was a joy to complete, even if it took me a bit more time because im not really good at geometry-based solving yet.

@G4M1L 2 жыл бұрын

Could you please elaborate on the pattern of equivalent sets you used - or point me to a video that showcases/explains it? I know the original Phistomefel's ring and one or two variants, but I don't see how any of these would cover 15 of the given 26 digits in one of its sets. Or is that not what you meant?

@evetheeevee2977 2 жыл бұрын

@@G4M1L I think it's something like this: (O being the boxes, X being the rings) X X X X X O O O O O O O O X X X X X X O O O O O O O O X X X X X

@Gandor1 2 жыл бұрын

@@evetheeevee2977 it took me a couple minutes to see what you did, but once I did, it just jumps out. That set leaves 6 open spots, 4 of them seen by the center 1,2 and the bottom left cannot be either the 1 or the 2. By giving both a 1 and 2 in box 7, the center acts like a key on the 4 spots it sees, leaving only the top right to contain the same digit. I wonder if the puzzle could have been set without the given 1 and 2 in box 7?

@Rangsk 2 жыл бұрын

A great puzzle by Qinlux (as always!). I'm really happy that Simon found the intended technique so quickly and cleanly. There's been a lot of innovation recently with the "Schrödinger cell" concept, and it's a great way to "fool" computers. Humans are great at seeing multiple overlapping techniques as one thing, but computers simply aren't programmed to do so. I think this is the simplest and most straightforward version of that I've seen so far!

@tessabrisac7423 2 жыл бұрын

So here we finally have the famously impossible Schrödinger cell! Welcome!

@mcg6762 2 жыл бұрын

A computer can brute-force solve any theoretically solvable sudoku in milliseconds. What we're seeing here is a computer programmed to mimic human solving techniques, used by constructors to check their work. Very different.

@mutantz6652 2 жыл бұрын

1 dislike so far - I guess that's from the computer

@davidbourke6211 2 жыл бұрын

I'll see your "overlapping finned x-wings" and raise you a "whatever goes in the central cell has to go in R1C9" That's what I named it! Took 19 minutes :)

@emonstermark699 2 жыл бұрын

Simon: "....we will be in clover!" Clover, the Sudoku Setter: "Oh, Bobbins!"

@TheWaddler 8 ай бұрын

Simon's ability to see these advanced geometrical patterns in puzzles is amazing, he makes it look so easy!

@zprmscorner1769 2 жыл бұрын

Each time I hear "as useful as a chocolate teapot", I think it would be nice to have a chocolate teapot for Easter. Too bad it would be a nightmare to ship, because otherwise it would have made for a fantastic seasonal merch for the channel.

@Coyotek4 2 жыл бұрын

My track record on 'Classic with a twist' puzzles like this is rather poor ... so it brings me great joy to have found the 'trick' to this one and solved it, in under 20 minutes no less (19:57 to be exact). Wonderful classic!

@samlawson5503 2 жыл бұрын

I like how 'The computer would have got that' almost becomes a constraint / logical step in these puzzles 😆

@btestware 2 жыл бұрын

Simon is correct to heap lavish praise on the puzzle-setter who can execute such a novel idea in such an elegant way. But he often forgets to mention one of the most amazing aspects of this type of design...that the puzzle-maker does not, in setting up the situation, inadvertently allow for a much easier pathway that avoids the intended set-up. Not only does the Qinlux avoid this pitfall, he sets it up in such a clever way that even a computer cannot find an alternate path without simply exhausting all possible options.

@Jodawo 2 жыл бұрын

He located two finned x wings after 22:45 and states I have got a digit and I didn't have to do anything complicated. I believe that was relatively speaking.

@necaton 2 жыл бұрын

considering the crazy logic he comes up with in other videos this was nothing complicated xD

@linachristiansen3349 2 жыл бұрын

The daily sudoku wouldn’t be the same without Maverick! 🥰 Thanks for all the hours of bringing order to chaos, Simon.

@raybrown2197 2 жыл бұрын

Phone call was Maverick telling Simon he's on the runway

@stevieinselby 2 жыл бұрын

At this point I can't decide if Simon lives underneath the flight path for Heathrow, or if he has one of his family primed to play an aeroplane on the speakers in the next room a few minutes after he starts recording...

@ragnkja 2 жыл бұрын

@@stevieinselby Simon really lives near a small airport.

@Leyrann 2 жыл бұрын

I'm gonna say this again: Alternating (spelling fixed, thanks Rangsk) Inference Chains are NOT guessing. They rely on a series of strong links (and weak links, again thanks Rangsk), which makes them tough to spot, but do not require you to think multiple steps ahead, in the same way a swordfish or a y-wing or an exocet doesn't require you to think ahead. The "guessing" techniques are dynamic contradiction chains, dynamic verity chains, region forcing chains and cell forcing chains. There might be a few more, but those are the obvious ones. (note: I do agree that puzzles that require more than one AIC have "no elegance" and actually dislike the technique as a whole - but it's not bifurcation) Also, while I'm early: Simon, _please_ take a look at the yzf solver, it's just so much better. It does require a download but that's not a big deal for someone who works with sudokus daily. Edit: Also, this is a beautiful puzzle. I will admit I needed some help from Simon to see it (I got it the moment he found the first x-wing), I blame it on being out of practice.

@Rangsk 2 жыл бұрын

It's actually "Alternating" Inference Chains because you alternate between strong links and weak links. I agree that it's not "guessing" but also in my opinion it's more a useful tool for describing and validating logic rather than something your average human solver is going to be happy to employ in every puzzle. Note I did say "average" - there are plenty of very good solvers who enjoy using raw AIC in their solves, but I think the general audience of this channel prefers more holistic and pattern-based logic like what Simon used in this video. Plenty of common patterns like the Y-wing, 2-string kite, and skyscraper can be described via an AIC and definitely aren't guessing, but I think people prefer to see them as patterns rather than being rigorous about describing the AIC underneath them.

@Leyrann 2 жыл бұрын

@@Rangsk Thanks for the corrections, and certainly agreed. I'll use an AIC when I spot it (and I do spot them sometimes these days), but whenever I do, I assume I'm not following the intended path.

@TheEricthefruitbat 2 жыл бұрын

I have to disagree. In general, you won't know the length of the AIC. Therefore, to get the result of the chain, you must follow it through an unknown length with unknown potential interferences along the way. Seeing what you get after trying a value for a cell is pretty much the definition of trial and error, which is what bifurcation is. I agree with Rangsk in that it is the theoretical underpinning or proof of finite patterns like x-wings and so on. However, they are fixed forms, and you do not need to follow the underlying chain to get the result.

@eternalblasphemy6526 2 жыл бұрын

@@TheEricthefruitbat One thing is brute force the chain filling it with actual numbers and seeing if it works (you throw whatever number and see if it sticks) and the other one is doing the same pattern within your head not putting a single digit before you make a deduction. This puzzle makes use of AIC - I was able to eliminate 7 in box 7 r8c2 thanks to AIC. I wouldn't call it bifurcation in slightest.

@TheEricthefruitbat 2 жыл бұрын

@@eternalblasphemy6526 It doesn't matter whether you do it all in your head or write it down. It is still a case of seeing what happens down the line when a specific cell is assigned a specific value. If a contradiction is reached, you eliminate that value, if not - either you learn nothing, or you solve the puzzle. That is trial and error.

@Kimakae 2 жыл бұрын

That was so lovely that I didn't know whether to laugh or cry

@lluissalva8689 2 жыл бұрын

First time I've been able to solve myself one of those seemingly impossible sudokus. Now I can taste the satisfaction Simon must feel every time he solves one of those!

@Pathogenus 2 жыл бұрын

I love those videos with classic sudokus. After discovering this channel and learninf about sudoku variants i started thinking that classic sudokus are boring. But those tricky techniques showed me that there's still something interstinf and challenginf about them

@RADZIO895 2 жыл бұрын

I'm actually kind of proud that I found the tech before simon's explanation (around 17-18 min)

@jonbrowne8334 2 жыл бұрын

I could see the 12 x wings with the fins quite quickly but just couldn’t fully understand the logic until Simon nailed it! Absolutely brilliant!

@SmartHobbies 2 жыл бұрын

Simon, you are amazing at what you do. I love the freshness you bring to each solve, especially ones that the computer solvers cannot figure out. I do feel inclined to tell you that Alternate Inference Chains are NOT a euphemism for guessing. They are advanced strategies based on solid logic that eliminate candidates. XY-Wings, XY-Chains, 2-string kites, and X-Chains, techniques you use on regular basis, are all forms of Alternate Inference Chains. Thank you again for all that you do for Sudoku.

@Vathorus 2 жыл бұрын

Another way to do this, without the "overlapping finned X-wing" logic is to play with colours a bit. And I'm going to try to write it down "in Simon's voice" because we're all so used to it anyway :P So let's ask ourselves a simple question: What is the centre digit, in R5C5? The answer is: I haven't got a scooby doo. But! Let's assume we do know what it is, and it is, let's say, purple. And now something funny happens in boxes around the central box 5, boxes 2, 4, 6, and 8. The purple goes into 4 cells, all rotationally symmetric with each other, creating this sort of double cross. And this is indeed very interesting. Because let's look at box 7 and let's ask: where the purple goes within this box? Well, what we know about the purple, is that it's either a 1 or a 2. And those two digits are actually givens in that box, so we can colour them purple. Now we can see they align quite nicely with other purples in boxes 4 and 8. So the next question we should ask ourselves is: where does the purple go in C1, and where does it also go in R9? They cannot go in boxes 4, 7, and 8, so they must go into boxes 1 and 9. And because of how the givens are placed, we can now make cells C1 R2,3 purple, and we can do the same to cells R9 C7,8. And this is quite beautiful because the purple aligns one more time, this time towards box 3. Because the purple in R1 can only go in box 3, and purple in C9 can also only go in box 3, it basically means, that the purple in box 3 must be in no other cell than R1C9! And it's absolutely gorgeous. Since we do know the value of purple - well, we don't know the exact value, but we know that it's either 1 or 2 and that it most definitely *isn't* a 9 - it means, that 9 doesn't go into R1C9, giving us a 9 in R3C7!

@siorac1147 2 жыл бұрын

This is much nicer than hunting for overlapping finned X-wings... though it still comes with the issue of 'how on Earth was I supposed to even think about trying to explore this particular train of thought?'

@Vathorus 2 жыл бұрын

@@siorac1147 I know, several months ago I wouldn't be able to find this train of thought myself. But watching lots and lots of Simon, and also getting their classic sudoku app is giving you some tricks. I basically noticed this while hunting for bent triples / Y-wings (the app teaches you to do just that, if you can't find any, you can always get hints which direct you to them). The only way to do that is try to find cells which have only 2 possible values, and align in a specific way. I found several of 2-digit cells scattered around boxes 4, 5 and 7. No Y-wings though. However I knew that 2-digit cells are weak spots in any sudoku and they ought to be focused on. Haven't got any luck with spotting logic in 2-digit cells of boxes 4 and 5 (I started with them, because they were aligning in some interesting ways, it seemed to be a red herring though). Then suddenly I noticed, that whatever this 1-2 cell in the middle was, it created this "double cross" pattern in neighbouring boxes. This definitely had lighted up some alarms in my brain, so I focused just on that, started to color stuff and see if it leads to any conclusions. Luckily, it did, and then the puzzle became way easier, when I could place 9s in boxes 2, 3 and 6 out of nowhere :) So I'm thinking you can get to this level too, if you just get more experience. Get the app, it has some challenging classic sudokus with hints enabling you to still solve them and follow their logic. Over time you will build the intuition, which can guide your thoughts to follow the useful patterns. Also sometimes coloring stuff can be very, very useful indeed, as you can get some conclusions about "where this cell can be in other boxes" even if you don't know what is the cell's value anyway.

@tessabrisac7423 2 жыл бұрын

Excellent pastiche! Thanks for the hearty laugh!

@V3n0mTV 2 жыл бұрын

This channel shows the beauty of sudoku and numbers in such a wonderful way. I'm so happy for finding Mark and you. Thank you!

@phyphor 2 жыл бұрын

Watching a solve path, especially with the false starts, is incredibly interesting and the reason I continue to watch your videos. Thank you for sharing them.

@inwalters 2 жыл бұрын

20:21-23 - "as useless as a chocolate teapot" - not true if you happen to be Prince Pondicherry. 😁

@andTutin 2 жыл бұрын

Setter: no Xing Simon: Double Xing

@Rubrickety 2 жыл бұрын

"This pattern with the 1-2-4 gives us two symmetrically-arranged finned X-wings which overlap in this corner cell, affecting the central cell of the grid - so I've got a digit, and without doing anything complicated!" 😂😂😂

@angelmendez-rivera351 Жыл бұрын

I mean, it isn't that complicated. Compare it to whatever on Earth the computer was doing.

@derx6666 2 жыл бұрын

I went on a search, but had to give in after pencilmarking the bunch, and not finding those finned xwings. This is an elegant solution sir

@G4M1L 2 жыл бұрын

Great puzzle indeed! I'm lacking experience in advanced techniques and looking out for patterns like that triple in box 7, so probably would never have managed to solve that completely on my own. However, once that was pointed out, my instincts - together with the hint in the puzzle's title - were telling me there was something going on with some symmetrical, crossing patterns. And when Simon explained the finned X-wing, I instantly checked the diagonally mirrored constellation and - voila! I paused the video, continued my own solve, which I had begun but unsurprisingly got stuck, and could complete it without further hints. The most amazing thing in this setup was, how relatively effortless the rest of the solve went, once you got just one crucial digit via a somewhat advanced, but not unreasonably complicated idea! Really amazing!

@longwaytotipperary 2 жыл бұрын

I had no idea the term "overlapping finned X wing" would be added to my vocabulary - much less that I would understand it (mostly)...😄

@glennmelven3414 2 жыл бұрын

We have gone back to the way things were a long time ago. Nikoli said they didn't like to have the Sudokus truly easy to solve once you found the breakin, and Simon gives Nikoli sudokus high praise. Now after the initial breakin Simon hopes for easy. Sudolu has become just like fashion, old fashions are in style again.

@willemm9356 2 жыл бұрын

I rather think this kind of puzzle is an exception to that rule, because it's a showcase of "hard for computers, easy for humans".

@ibrown 2 жыл бұрын

What a lovely way to finish the week.

@necaton 2 жыл бұрын

wait...am i stuck in time by 2 days?

@necaton 2 жыл бұрын

or do you imply that this sudoku gonna take you 2 days? xD

@ChilapaOfTheAmazons 2 жыл бұрын

Managed to solve this in 31 minutes without bifurcation, got lucky and noticed that there was something fishy with R1C9 but I couldn't have explained it as elegantly as Simon did. 😇

@kathyjohnson2043 2 жыл бұрын

Something "fishy"?

@ChilapaOfTheAmazons 2 жыл бұрын

@@kathyjohnson2043 well, I noticed that if it wasn't a 9 the puzzle would make a lot of progress, then I noticed that it could be a 1 or 2 like R5C5 and finally I realized that it had to have the same value as R5C5. As I said, I was a bit lucky because I could have easily missed one of the links but this time I solved an hard puzzle much faster than I usually do.

@VeritasUnae 2 жыл бұрын

What a beautiful technique! It's wonderful to see those two fins collide in the murky depths of the sudoku squares, 1 coming off the victor. Well solved Simon, and expertly set, Qinlux!

@maxparkinson1265 2 жыл бұрын

We add RCD to Simon's 'silent shout-outs' to great tracks, following East Lake and WH. I'm jealous.

@sully55921 2 жыл бұрын

I'm on call this weekend, and when Simon's phone rang my heart dropped for a split second until I realized it wasn't my phone.

@alakario 2 жыл бұрын

The names of some of these techniques are so weird and funny!!

@joubess 2 жыл бұрын

Qinlux, standing ovation to you!!! Please take a bow!

@Indiapapa100 2 жыл бұрын

Maybe it already exists, but I think a cool video/series would be one breaking down some of these like tough strategies. Like an explanation of the strategy at the beginning and a n example or 2 of where it is used in a puzzle.

@danieltaber4924 2 жыл бұрын

I have found a trick on this kind of puzzle! When you have a puzzle that computers can't solve without guessing, and its clue placement is diagonally symmetrical, the key to the puzzle is always on that diagonal!

@rupen42 2 жыл бұрын

I feel like you always find a new way to explain X-Wings. That's so nice! It probably helps people who didn't learn it well in a certain way and it's entertaining for those of us who already know what it is.

@SnowTheJamMan 2 жыл бұрын

That Sukokult pdf is glorious, already solved thie first puzzle (33 minutes), gonna try to solve them all especially since i'm not that great at classic sudoku

@thomasbui6175 2 жыл бұрын

I like how the title: No X ing is quite literal because you have 2 orthogonal X wings that make a 3rd, larger, X in a way. But you cannot allow that.

@Mephistahpheles 2 жыл бұрын

Overlapping finned x-wing. OMG! Brilliant!

@maspleben 2 жыл бұрын

That was beautiful to watch. Such a simple pattern and yet deadly for the computer. Fabulous.

@cmonkey63 2 жыл бұрын

It's puzzles like this that make me happy to be a Patreon supporter.

@shawnward6607 2 жыл бұрын

New idea for CTC merch. Chocolate Teapot shirt... and how its very very useful. Otherwise excellent solve Simon.

@bobblebardsley 2 жыл бұрын

This is lovely. I didn't attempt to solve it myself (and I would have failed if I tried) but the centre cell stood out as 'weak' from all the digits pencil marked into the box, so I can see how the solution was signposted, if you knew what to look for. Really sweet.

@TomHickey 2 жыл бұрын

22:46 aka "Take that, machine!"

@BruceSchwartz007 2 жыл бұрын

Brilliant set! Brilliant solve!

@newsusa3489 2 жыл бұрын

I have recently become a fan of your channel and oh man, I cannot stress it enough how happy I am with the uploading speed haha. It is so unique real :)

@sunriselg 2 жыл бұрын

At 21:48 I started laughing like crazy. This technique is insane!

@ilonachan 2 жыл бұрын

Finally took a look at the techniques the solver uses. Seems like formal renditions of certain common types of short-term bifurcation: trying a digit and seeing that it contradicts itself (closed cycles), or coloring two different options for certain cells in the grid, then eliminating the stuff that wasn't true in either case (the Medusa). I'm sure giving these names and structure makes them easier to spot for _some,_ but I personally think that looking for medusas specifically is something only a computer would do. Still cool to know that has a name.

@mcg6762 2 жыл бұрын

That's ironic because what we're seeing here is a computer programmed to mimic human solving techniques used by constructors to check their work. If you want the computer to solve this fast you just let it brute force solve it and it's literally done in milliseconds for any theoretically solvable sudoku.

@ilonachan 2 жыл бұрын

@@mcg6762 yea, the thing is, this is absolutely one of the ways a human could solve a puzzle (if they spot it). And when the computer presents the Grouped X-Cycle all laid out I can easily understand why he's right, and that this isn't just brute force guessing! The main problem here is that humans would spot a variety of different things before just attempting a cycle on every pencilmark. Like Simon who just kind of invented the easily understandable "overlapping finned X-Wing", rather than finding the Alternating Inference Chain underlying that pattern. The computer just kind of has to go through his list of (theoretically human-findable) techniques to _approximate_ that ingenuity, and the result can never be as pretty.

@doris1826 2 жыл бұрын

"About as useless as a chocolat teapot" is likely a very common expression in Britain, but here in the US, it is amusing, & is inspiring me to experiment with some sort of exotic ice cream topping or Sundae!

@jeffreytennant 2 жыл бұрын

Absolutely beautiful logic

@BozoTheBear 2 жыл бұрын

Utterly brilliant!!!

@davidalderson 2 жыл бұрын

Clever setting, brilliantly explained by Simon.

@samplename5159 2 жыл бұрын

My educated guess was correct - the puzzle hinged on the placement of 9 in box 3, i found a coloring scheme that allowed me to confidently and wrongly accuse the 9 of being in the broken cell and a few minutes later the puzzle told me "nope", but in such a way that the finned X-wings became clear as day and restarting lead to understanding the concept. Amazing construction.

@TonyT57 2 жыл бұрын

Simply fantastic - both the puzzle and the solving with crystal clear explanations! Thank you!!!

@vincentdesiderio767 2 жыл бұрын

A gorgeous puzzle.. Cracked it the same way you did Simon.. Bravo 👍

@v3lojt 2 жыл бұрын

I liked this walkthrough of the puzzle. It was very informative. I like learning the techniques this way.

@stephenpassmore7306 2 жыл бұрын

Stunning break.

@ColinHolloway70 2 ай бұрын

What an awesome puzzle!

@itsomni 2 жыл бұрын

I love watching these videos and solving along with you. I don't know all of the techniques (yet!) but it is nice to refer to the videos when I find myself stuck or frustrated. Only had to refer back to the video twice this time, though it did take me over 40 minutes to solve with your help haha

@Pdt8000 2 жыл бұрын

My time was 20:06; I'm pretty happy with myself for seeing all the components of the trick, even though I had to use the hint from the title to investigate it further. Great puzzle, great channel lol

@gposchman Жыл бұрын

I figured it out, but I really don't have a strong knowledge of finned xwings. I found the 2s in column 1 and the 1s in row 9. The name bothered me because it said no Xing. I found the two xwings and then I found the middle square. From there I deduced that the corner had to be a 1 or a 2 and couldn't be a 9. I was over joyed. You two have taught me so much. What a great puzzle. I guess the computer solver doesn't know negative logic.

@eatdirtmofo 2 жыл бұрын

Setter, Genius. Solver, also Genius.

@slb050568 2 жыл бұрын

Definitely a great classic! Def take a bow gentlemen: both the setter And the solver! 😁

@kenadams2475 2 жыл бұрын

One idea: In the end, go back to the computer and just give it this one extra digit. I think it would be nice to see how it now always stays at the "easy steps".

@martingibbs1179 2 жыл бұрын

Took me awhile to find the trick but I did find it myself. The title was a big clue so I was looking for x wings from the start but just not finned x wings!

@Randomguy547 2 жыл бұрын

I came within a nanometer of figuring it out, but I broke something re: the finned x-wings along the way. This was my first time playing the puzzle before watching the video and I appreciate the puzzle and logic far more now that I'm doing it.

@In.New.York.I.Milly.Rock. 2 жыл бұрын

"Lunacy steps" 😂😂😂😂

@lizzzylavender 2 жыл бұрын

I got the three easy digits and just couldn’t see anyway to proceed, so I came here to see how it’s really solved. I guess not everyone is smarter than a computer lol

@superdan2593 2 жыл бұрын

Absolutely brilliant! I can't imagine people disliking this video but it has been proven that either like or dislike is good for youtube stats so why not? :)

@Sibula 2 жыл бұрын

I first found the suspiciously symmetric possible placements of 9s and when I couldn't force any digits with that information I checked what else could be interesting about those cells, finding the finned x-wings. Very enjoyable puzzle.

@zeargo 2 жыл бұрын

Although I did find another method to place a 9 in Box 4, which allowed me to place numbers on the left side. I eventually caught onto the technique after watching up to about 16mins in, which made me very thrilled as I got to complete this one. The previous one I did see it, but couldn't solve it. So I am glad I saw the technique and solved this one.

@f.w.7843 2 жыл бұрын

So beautiful!

@mostman 2 жыл бұрын

Stunning.

@Anione111 2 жыл бұрын

This level of complexity is way out of my league! Even with the colour coding and great explanation, it took a while to grasp. How does one crack it without all that??!!

@tman9641 2 жыл бұрын

Thanks again Simon!

@AvatarBowler 2 жыл бұрын

I doubt this matters to most people, but my guess is that the puzzle title means “no crossing” rather than just “no Xing”. 🤷‍♀️

@onlyonewayrm 2 жыл бұрын

A heavy dose of Goodliffe-ing and a video clue later I managed a healthy 22.55 🤣

@RobertLeyland 2 жыл бұрын

Solved by sorting out the 9s. There were forced eliminations, leaving an impossible X with the only solution being at 9 in the bottom left corner. I’m a bit slow so this was 26mins of pure fun.

@eatdirtmofo 2 жыл бұрын

Ha ha, as Simon punches Computy-McCompute-Face in the kisser....

@jdyerjdyer 2 жыл бұрын

I saw several almost x-wings, but missed the logic here. I did see the 12 in the center of the grid, thought it weird, but didn't see how. Came to the video and as soon as you mentioned that triple, I knew, just knew it was suspicious, so I paused, saw the conclusion that R1C9 was forced to reduce forcing the 9 and done. It unwound quickly from there. :) Very nice puzzle, but I think I could lose a day not seeing that logic myself had I not gotten the hint. Great spot, Simon!

@bobbobson6867 2 жыл бұрын

Need to teach the computer about symmetry and spotting patterns. I had a feeling it was something to do with the 1's and 2's because they are symmetrical with each other. Not impossible to teach the computer this but it is on the way to being a General AI when it is that good.

@strifera 2 жыл бұрын

There was another way to solve this without the overlapping fins. Once you'd narrowed the center to a 1 or a 2, either would have eyes on 4 of the only 5 remaining spaces needed to complement the 1 and 2 in the lower left via the Phistomofel-like breakthrough you taught us in Steering Wheel. The one unseen space is the upper right corner, and therefore the upper right corner must match the center as either a 1 or 2, eliminating 9 and leading to the solve.

@JalebJay 2 жыл бұрын

It's very interesting. If you recreate the puzzle, but plug the 9 of box 3 in, it breaks the puzzle for computer solvers immediately.

@benspringer6880 2 жыл бұрын

My favorite puzzle.

@theblackswan84 2 жыл бұрын

i'm not really sure why but when you say "bobbins" i laugh a lot :)

@bluerizlagirl 2 жыл бұрын

I suppose if the computer was never explicitly programmed to handle a finned X-wing, it might have to follow a few chains of deductions in order to eliminate what the finned X-wing eliminates. It seemed to go around the X-wings a few times with its deductive chains, whittling away candidates one at a time, until it found the eights and nines and entered the endgame. I suppose it doesn't look elegant because without knowing straight away where to look, it has to pick the starting cells for its chains of reasoning in some strict order. Shades of Eric Morecambe playing all the right notes, just not necessarily in the right order .....

@eternalblasphemy6526 2 жыл бұрын

If you want Sudoku Solver to be elegant, you have to take out AIC and Medusa in such puzzles, else all you'll get is either Medusa, AIC or (in extreme cases) Digit/Cell Forcing Chains. I usually turn them off around 270-300 difficulty.

@Raven-Creations 2 жыл бұрын

That was really interesting. The key for this to work was not so much the overlapping finned x-wings, but R5C5 being limited to 12. I can understand why the solver couldn't get this, because each x-wing on its own didn't really do anything, and even together they wouldn't, if R5C5 wasn't restricted to the two digits involved. I do find this series interesting, but I can't imagine seeing these techniques in too many puzzles. They seem to belong in the sudoku curiosity box, rather than the sudoku toolbox.

@jimjimellell 2 жыл бұрын

I solved this using the same techniques that the computer did, but I did not notice any guessing, no elegance, mad geometry lesson, crazy, mad, or lunacy steps. Did I miss any other bashing? Ha Ha ! Simon's solve, however, was brilliant (as usual) and I am so impressed with the new "Sudokult Gospel" giveaway of 54 FREE high quality puzzles by top notch setters that I am marching right over to the patreon page and plunking down a donation which I have been remiss in doing for several years now. Maybe then the Discord Server will let me in without demanding my personal info up front.

@jimjimellell 2 жыл бұрын

Never mind! The patreon page does not accept one time donations and asks for too much personal info. Thanks for all the free puzzles anyway!

@littleschnitzel8226 2 жыл бұрын

What a beautiful puzzle, I'm really glad I solved this one. Took me almost 38 minutes, but the discovery of the possible 1s and 2s x-wings and what they lead up to was rather beautiful. Hats off to the setter! Edit: It's funny how I got the break-in in a few minutes and then struggled to see the rest, whereas Simon took his time with the break-in and then smashed through everything in an instant. :)

@eatdirtmofo 2 жыл бұрын

Great name.

@bermchasin 2 жыл бұрын

i dont think you actually did it. The rest of the puzzle was so easy in comparison to the flagged xwings.

@littleschnitzel8226 2 жыл бұрын

@@eatdirtmofo Thank you kindly. :)

@littleschnitzel8226 2 жыл бұрын

@@bermchasin Tried to give you a proof, but yt autodeletes links, it seems, to me anyway. I'm quick with the logic, terribly slow with scanning, though, like the naked 3 in box 6 was staring at me for good 10 minutes. :)