A Brand New Trick For Very Hard Sudoku Puzzles
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Күн бұрынThanks to Derek Neal for this extremely interesting new method he calls "The Slot Machine". You can try the puzzle shown in the video here:
cracking-the-cryptic.web.app/...
This puzzle is taken from the Brainium Sudoku app and you can find out more about the app at these links:
App Store
apps.apple.com/us/app/sudoku/...
Google Play
play.google.com/store/apps/de...
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▶SOFTWARE◀
We sometimes use Duncan's Sudoku Solver, which is available at www.littlegogs.com/index.shtml
Or our own software, which you can access by clicking on the links under the video.
▶ABOUT US◀
Hi! We're Simon Anthony and Mark Goodliffe, two of the UK's most enthusiastic puzzle solvers. We have both represented the UK at the World Sudoku Championships and the World Puzzle Championships. We're also "cryptic crossword" aficionados. Mark is the eleven-time winner of The Times championship and Simon is the former record holder for most consecutive correct solutions to The Listener crossword. We hope we can help your puzzle solving while also introducing you to some of the world's best puzzles.
Thank you for watching!
Simon and Mark
@msclrhd 5 жыл бұрын
If you look at the logic for the X-Cycle from the solver at 1:49, that is the same as the logic with the 5s at 5:44. This technique looks like an interesting way of easily identifying a subset of X-Cycles.
@Goryus 5 жыл бұрын
Interestingly, the Swordfish the solver finds also eliminates the exact same set of 1s the Slot Machine did.
@kristofersokk1580 5 жыл бұрын
This is genius, it makes total sense. I've had the intuition myself that following one number and its possibilities can give results but I haven't put much attention to trying it out myself.
@draconicdusk5911 5 жыл бұрын
This is genius and so much FUN to use. not only that, it becomes so much more potent the more other numbers you have filled.
@SudokuSwami 5 жыл бұрын
Well, I realize that you guys like to solve puzzles without using automated and complete Candidate Lists. So this is a very interesting technique. It strikes me as a Trial & Error method. Right? Similar to Forcing Chains. I especially like the idea that if you can construct 2 chains with no contradictions, based on opposing premises, you can then eliminate the "elbow" Candidates, as you call them. But I must say, after you filled in all the Candidate 5's at 4:41, it was immediately obvious that you had a Sashimi Swordfish in Rows 3, 6 & 9, allowing for the elimination of the 5 in R4C7, which then leads to the solution of the same three 5's that you eventually found, but with a lot less rig-a-ma-role. And then at that point, if you are looking at ALL the Candidates, the Puzzle just falls apart, and is nothing but Singles, except for a set of Locked Candidates on 2 in Column 5, about 2/3 of the way through. So really, just the one move, at the very beginning, solves the whole puzzle. But, to each his own, I guess! Ha-ha. There was also an obvious Standard Swordfish on the 1's when you filled them in, (again in Rows 3, 6 & 9), but after solving those three 5's, you didn't even need it. :-))
@hotonis 5 жыл бұрын
So I do a ton of Sudoku puzzles on an app that generates. And this happened in the hardest difficulty after watching the video. It gave me an immediate break on the puzzle and was able to solve it in less then 10 minutes for the first time. I love this new method and thank you for sharing!
@Goryus 5 жыл бұрын
Congratulations! Glad it helped.
@petemagnuson7357 5 жыл бұрын
comparing the 1 and 5 examples with the steps the solver was taking, it looks like the slot machine is a more human-friendly way to find identify certain X wings and X cycles.
@Goryus 5 жыл бұрын
Yes, it is a human-friendly way of finding x-cycles.
@Kyrelel 5 жыл бұрын
I am not a Sudoku master - far from it. I am self-taught, sadly, by being forced to wait for my partner to turn up - sometimes 2 hours late!!! - and decided to do puzzles in the mean time. I came across this channel a few weeks ago as it appeared in my suggestions list, and I have watched 3 or 4 of the videos. Imagine my surprise to find that this "new" technique is one I have been using for over 10 YEARS !!!
@sjege 5 жыл бұрын
Yeah, same here. But I allways gave up when there were 4 in one 3x3 😅
@philippequintard2378 3 жыл бұрын
same here ( i would not say 10 year , more like 1 max) but I'm a novice, I've seen the x-wing, swordfish on this channel not long ago, and have a lot of trouble to use them. but i use the " slot machine" but isn"t it just a diminished form of trial and error
@FF_Fanatic 5 жыл бұрын
I'd be interested in hearing Mark's thoughts on this. It has that guessing element that he's spent so much time mastering in order to quickly solve his puzzles, and I'd like to know if there's any overlap for him or if he has anything to add.
@Malygon 5 жыл бұрын
Oh wow, I've been using that technique for years but I didn't know that this wasn't well-known and I also didn't know what the ideal conditions were for this technique to work, as in having exactly three numbers in positions so that each square is affected by 2 numbers. I just used it whenever I saw numbers forming loops like that. Now I can look for it more actively!
@danielhughes3758 5 жыл бұрын
Same. I never called it a "slot machine technique", I just called it "testing numbers". I would randomly test numbers and it would sometimes help sometimes not. I've never seen the possibility of eliminating the "elbow numbers" or the idea that I should start with a number that has exactly one in each column and row as well as specifically 3 in total. This makes the method I figured out how to use so much more efficient because I know where to start looking.
@muddrosal8065 5 жыл бұрын
Ditto! I considered it a kind of 'whittling' as I used it mainly to cut out pencil marks when I was at a standstill. Admittedly I would just march through each number testing the marks against each other until something new revealed itself and then I would do it again.
@PrometheusZandski 5 жыл бұрын
Yep, this is called guessing. I think most people discover this after a few months.
@shadowwalker2336 5 жыл бұрын
That's an incredible technique. I tried staring at the grid for 5-10 minutes with just a few pencil marks to show for it. I used the technique discussed and solved the whole puzzle from a fresh timer in 16 1/2 minutes
@SonnySandberg 5 жыл бұрын
Okay, first time using that method and I cracked the puzzle you provided in 27 minutes. I was able to use the method on first 5, 1 and 8. Gave me a little each time. Then by doing normal sudoku and usual methods, no x-wings and all the other stuff, just the easy methods always shown, it was cracked open. I do not regard myself as a fast solver. I am very impressed by this method.
@-siberian- 5 жыл бұрын
I tried this technique on this sudoku. Now I imagine this sudoku was made for this technique, as this completely solves itself once you go at it. I will have to try this in some of the sudoku's I could never even come close to solving with the more traditional techniques I know. But honestly love this technique already!
@emorgan0085 5 жыл бұрын
The "closed loops" always satisfy at least one of the following properties: a) the loop can be broken down into multiple sub-loops, or b) you can eliminate enough possibilities from each box so that at most only 2 locations remain.
@PrometheusZandski 5 жыл бұрын
Like many others on this comment board, I too have been doing the same thing for years. It's called guessing. It's highly educated guessing followed by execution of it-then-else logic to find a contradiction. It's much more powerful when you involve two numbers that are bound together, because then you discover two number chains at once, but this can also be very effective. If this is what you need to get a doctorate in Sudoku theory, then I think half of use deserve one too.
@JaggerG 3 жыл бұрын
It starts as guessing, but as the explanation goes on, there’s some further theory that comes out of it. I’ve noticed in another puzzle, just guessing a position actually led me to discover number in the same cell as a direct result of either guess, so I got to undo all the guesses and just fill in the one result. I do usually save “guessing” for last, though.
@jdoe834 4 жыл бұрын
Super cool! I actually do this technique myself, but only as desperation, because I never realized having the set of 3 numbers like that are what enables it. Knowing that makes it so much simpler to intelligently incorporate into my solves! I tried this myself before watching, and did find the "slotmachine" on 1s, but only after much head scratching over all the things I couldn't do. Hopefully next time I spot it sooner!
@CaptainHandsome 5 жыл бұрын
One minor observation I have is that if you look at the grid with the 'elbow' cells highlighted, if you imagine placing a 1 in any of the elbow cells it eliminates both the other elbow cells. The same also seems true with the 5s, and placing the correct 5 as shown in the video seems like the only possible move that doesn't eliminate 5 from any of the elbow cells. I could be totally off base here, but maybe it's something worth considering.
@olemification 5 жыл бұрын
I believe this technique works well on any loop with at max 3 candidates within each 3x3. The 3 numbers in different 3x3 column/row is not the limiting factor, but it certainly makes it easier to find candidate loops to solve. You could also achieve similar loops where ever you have locked the candidates of the necessarry squares. I've sort of been doing this technique, but have been struggling to identify when the technique might be fruitful and when it's not. Derryl's insights definately will help me improve. Great work, thanks Derryl!
@karfaw2 5 жыл бұрын
Thank you for this new technique. It's very interesting and I never saw it before in any Sudoku solving techniques book.
@MNNocete 5 жыл бұрын
I can hardly see the cursor or pointer. I wish it can be made more visible.
@fiasunes 5 жыл бұрын
I actually am using this quite often especially when I reach a point where I can't go on. But I didn't put much logic in it, because I felt like cheating since I would start guessing and trying. Furthermore I never learned any advanced soduku skills like swordfish and the likes. On the soduku app I'm using, I even set my personal records with this technic and got roughly 7 minutes as a record on the hardest difficulty level.
@williamwester9203 2 жыл бұрын
Going back in time to solve some classics that pre-date my finding the channel. Like others, I feel I use a variation of this technique without calling it as much. The presence of 3 numbers in separate "3x3 rows" and "3x3 columns" is something I look for when I'm stuck. I use a color to highlight possible cells. It helps me spot swordfishes. If no swordfish, then I look for a 3x3 with only two cells where choosing either option "knocks out" two possibilities in another 3x3. Using different colors for the two "chains" allows me to eliminate cells where both colors point (i.e. elbow cells).
@crazypomp927 5 жыл бұрын
This is fantastic! I wonder if this could even help with tackling computer generated puzzles that would otherwise be unsolvable for a human without guessing. EDIT: I wanted to report that I just used this technique for the first time, and the result was AMAZING! I was completely stuck pretty early in the puzzle, and this technique allowed me to fill in a 6, which then unraveled a massive string of 22 numbers! That's right. I went from completely stuck to placing 22 digits. It was so hard to believe I had to turn on the "check for errors" feature to make sure I hadn't screwed up, but it was all correct. And with all that progress in one go I quickly finished the puzzle after that within a few min. Incredible technique! I don't expect that kind of result every time but it demonstrates the huge potential this has.
@Goryus 5 жыл бұрын
Awesome! It's great to hear stories of situations where it helped people.
@crazypomp927 5 жыл бұрын
@@Goryus thank you so much for the technique! It took an "Expert" rated puzzle I had been staring at for 30 min and completely trivialized it.
@dejanlupo 5 жыл бұрын
I like it. Congratulation Derek and thanks to Crypticcracking.
@helenscott8202 5 жыл бұрын
Really interesting technique! And I am delighted to have any other techniques to try. Thank you!
@jrmitchell12 5 жыл бұрын
I did the linked puzzle so fast, it was amazing. Great technique.
@pam5256 5 жыл бұрын
You should make your mouse pointer bigger,, and brighter and more obvious, maybe add a colour very different from the background. I can't follow it, as you zip around the screen.
@AK-dp8uy 5 жыл бұрын
Yes. Please change pointer to the windows inverse large
@Shuey187 5 жыл бұрын
This is freakin' awesome! Thanks so much for sharing it!
@ctsirkass 5 жыл бұрын
I have been using this technique as long as I can remember, but never from the start like this, mainly because the puzzles I solve are not diabolical. It was always a sort of last resort for me in order to eliminate "elbows" but it rarely revealed whole sequences of numbers. Interesting to see it being formulated as a system in its own right. It's also interesting to note that this technique works best for people like me that like solving puzzles without pencil marks.
@unexpectedparolemadwerewol6565 5 жыл бұрын
This is a very interesting technique. I've been tempted to go towards a route like this, but without identifying the 'only 3 numbers in each of the 3 rows/colums. restriction. That goes more towards guesswork. With this restriction though you are essentially notating for the x-wings, swordfishes and other complex arrangments. It's essentially the way to isolate each number on the puzzle and check for those relationships without the clutter of everything else. More later probably after I dig in more. thanks !
@gposchman 5 жыл бұрын
I tried a different one set, upper right square and using one of them I failed but the other gave me some modest success. I then did the same with the eights. Following basic processes without any other solvers except matched doubles, I was able to solve the puzzle. An interesting tool, look forward to trying it out.
@malloryrobinson6418 5 жыл бұрын
neat technique! Thanks for sharing :)
@tracewallace23 5 жыл бұрын
Thanks Derek😎 PS. You might try a larger/more colorful cursor. Sometimes it's hard to see where you're "pointing"
@ThatGuy-dj3qr 5 жыл бұрын
Always exciting to have a new trick in the bag!
@isaacbooth210 5 жыл бұрын
Wow. This crazy. My grandpa was the first one to teach me sudoku and I noticed this. He said it didn’t work so I agreed and I use it now whenever I can. It kinda made sense to me but this makes it click and it’s easy to explain. Thanks
@stefanholbek2449 5 жыл бұрын
Wow ... After having studied 50 Swordfishes I STILL DON'T get it !!! ;O) And yes, I tried this puzzle myself with Hodoku, and it came up with a Swordfish as the FIRST step ... which should tell how tuff the puzzle is. I wrapped my head around it, and I think I understand it better now, but spotting them myself may take another year or two ... Now: This "Slot Machine" is EASY TO UNDERSTAND, even for someone like me !!! So yes: A BIG thank you to Doctor Neal!
@jons2cool1 5 жыл бұрын
Finding swordfish without full pencil marks is very challenging. If you are using full pencil marks; however, sudokuwiki does a great job explaining swordfish and after an hour or so they should be very easy for you to spot. The most important thing to know about a swordfish is they can be compromised of 6 to 9 digits, a 2x2x2 up to the perfect 3x3x3, with any combination in-between.
@jonnybolton4659 Жыл бұрын
I've done this method loads just never thought of it as a specific method! Although this is 3 years down the line so who knows how much sudoku methods have evolved in that time. My method for spotting the cells which can never work is to colour each cycle one of two colours (i.e. pick one starting cell, colour it a colour and then colour each option that is still possible in that loop - noting that sometimes more than one cell in a box is possible, then repeat with the second loop and a second colour, everything not coloured you know cannot contain the digit)
@bobstevenson1970 5 жыл бұрын
WOW! this is really great! I can't wait to try it!
@adambarrett6907 5 жыл бұрын
Very cool. I’m going to try this next sudoku puzzle I play. I noticed the symmetry!
@kiraPh1234k 5 жыл бұрын
This is basically the only strategy I've tried in Sudoku - Now I've only solved them casually but this always seemed like the basic approach.
@BryanLeeWilliams 5 жыл бұрын
This is so cool. Unfortunately none of the puzzles I've done since this have been candidates for this method
@Destructificial 5 жыл бұрын
Interesting approach! I was able to figure out the 1-loop on my own, but got stuck after that and started watching the video. With the single 5 given by the solver, it became a rather trivial puzzle.
@oromis1221 5 жыл бұрын
It seems like if you apply the elbow rule and then start from the center on the last puzzle with the 1s, you can eliminate one of the 1s in the pair in the center square and get all of the 1s on the board. I’m not sure if I’ve overlooked something that means you can’t assume that, but I think it should hold...
@arcynical8053 5 жыл бұрын
It's so awesome that you just put the puzzle in the description. I'ts so easy to just try now
@ronaldodimaano8641 5 жыл бұрын
This is revolutionary. Thanks.
@supermills03 5 жыл бұрын
Well now I spend my time looking for these at the start of every sudoku, get excited, work them out, but so far every time they are useful I find I could have gotten the answer quicker with regular sudoku, I guess it's really only applicable when you can't even find any digits, do some quick sudoku first, and then look for the slot machine if you have no luck maybe. Edit: right after I posted this I found a puzzle that the slot machine worked beautifully after fussing with it using normal tactics for 10 minutes.
@magiclarry7688 5 жыл бұрын
Definitely another useful attack sequence to solving a puzzle.
@PanterD2S 5 жыл бұрын
Thought I was already doing this "chain falsifications" in case i got stuck - but the new thing seems to be that 3 point arrow motive/pattern that comes with those 3 5s 9s 1s 8s. One in a corner and the other 2 in a middle part and then just count if theres not too many solutions with 4 possibilities on the way... got it...might work...gonna check it out ;)
@ianwebster995 5 жыл бұрын
You can also use empty rectangles at the outset from nonets containing three possibles, instead of chaining. This very quickly led to six known 5s instead of the opening three in the above puzzle.
@rogerwprice 4 жыл бұрын
mind-bending! Thanks!
@ChessRabbitt 5 жыл бұрын
Lol. Right where you said "I don't know the computer is doing here." is when the computer used this technique to slove the problem. Very good indeed. Watch the video again and notice the 5 line the computer use.
@EquiliMario 5 жыл бұрын
That technique tries to find a sequence of locations where, by removing a potential location, that location is required in the sequence. This new technique tries to find a sequence of locations and determines which locations are fixed or impossible. It's not entirely the same, but they both require sequencing of locations and creating a result by elimination
@andrewgedge4015 5 жыл бұрын
Awesome technique for a fairly common situation, even in "easier" puzzles. One suggestion I would make in terms of teaching techniques is to also present examples where the technique could not be applied. You mention the needed orientation of the 3 starting cells, but a visual example of an arrangement that does NOT qualify might be helpful for visual learners. Thanks so much for continuing to help us all develop!
@fingerling1231 5 жыл бұрын
Very nice trick. After watching the initial explanation I tried the puzzle and it only took 8 minutes.
@WickedPissahVideos 5 жыл бұрын
Ironically, rather than adding this as a tool of last resort, it's better employed early on. Completing the puzzle too far might eliminate opportunities to use this later on. Brilliant concept, Derek! Thanks!
@Birchbayaromatics 4 жыл бұрын
really really really enjoyable. thank you
@zanzaboonda 3 жыл бұрын
This is super cool. I've noticed some of these patterns (or something kind of similar, like elbows and stuff in the corners) but never knew what to do with them and definitely never would have broken it down like one number in each row/column, etc. (I would not have discovered this on my own.) Everyone thinks differently, and I can really see this helping for some puzzles! Can you put together a compilation video that shows all that different techniques? E.g., just pieces of your previous videos? We don't need a whole solve. But 'chapters' would be great.
@simovihinen875 5 жыл бұрын
Can't believe a new sudoku technique that I could easily understand was found... and conversely that such a simple technique hadn't been found before. This is almost something I can picture myself starting with if I got into sudokus.
@Aragorn.Strider 5 жыл бұрын
I came to the same idea by myself, when I was blocked on one, when I was playing an Expert puzzle, and with conventional ideas I didn't make any progress. Eventually in this way I managed to cross out some solutions, and finished it. However, it can easily become daunting... This video did gave me some small tips though, thanks!
@caulerpa1 Жыл бұрын
This is so cool. At times it's almost impossible to figure out those AIC chains. This technique can come in handy
@4sawzer 5 жыл бұрын
Fascinating!
@simont17 5 жыл бұрын
very powerful technique, was able to fill all 5s and 1s and 8ths (except 2 boxes) before adding any other number
@brucejones533 3 жыл бұрын
Great technique!
@carlosmarino2678 5 жыл бұрын
Very interesting, I'll have to try it. I'm fairly new at this, what software are you using? Thanks.
@2218256 5 жыл бұрын
Anyone finding many puzzles that present a slot configuration at start? I have gone to my favorite book, Puzzler Monthly and favorite apps (Sudoku Prime and Sudoku Joy) and it is rare that a puzzle starts with at least a single number in ‘slot-machine’ configuration. I am competing in National Champs in a couple of months and need to decide if this is valid and quickly and easily identifiable step for speed solving the harder puzzles. Thank you for the endless passion Simon and Mark.
@speadskater 5 жыл бұрын
love this!
@OriginalThisAndThat 5 жыл бұрын
I found this method out by myself times ago. Never actually watched any sudoku based tips from anywhere. After solving some numbers you can start doing 1-9 box and whole line logical thinking and its all done easily.
@TheRealDrWho 5 жыл бұрын
Thought this was the normal way
@TechlogicProductions 5 жыл бұрын
Darren A. Chilton I was thinking the exactly same thing, like WTF? How did this guy solve anything WITHOUT using this technique! That’s what I want to know atleast
@vidalschneider 5 жыл бұрын
@@TechlogicProductions by elimination
@MagicScorpio 5 жыл бұрын
The end of the video was more of my normal way. The beginning rules he had with three of one number in 3 rows and 3 columns was interesting to me. The whole elbow thing was a good way of putting off. Also liked how he showed one loop with a contradiction and one where both options worked. Very good video sir
@TechlogicProductions 5 жыл бұрын
Vidal Schneider No difficult sodoku can be solved with elimination alone AFAIK, also, this technique is basically just an advance type of elimination, right?
@vidalschneider 5 жыл бұрын
@@TechlogicProductions you didn't ask how he solved hard puzzles tho, you asked how he solved literally anything without that technique, as if there were no other ways. I just told you one of many
@kenthemaster 5 жыл бұрын
Derek's screenshots look like they were taken of an Expert level puzzle from a mobile app called "Sudoku by Brainium". I've seen quite a few examples of Expert puzzles from that app which fulfil the prerequisite (3 numbers in nonets of non-intersecting "rows" or "columns"), so I believe this technique would be pretty useful on them.
@sandrachurchill1375 5 жыл бұрын
Yes! I use that app, at expert level, and currently working a puzzle where I can apply this technique. 👌
@jkn6644 5 жыл бұрын
I have similar system: Investigating number n. From 3*3 sub-squares look for cyclic pattern. If all ns are on same row or column, this 3*3 square cannot make a turn. Pattern like / or \ or L (and rotations of L) do make turn. If these turns form a cyclic pattern, then there is a possibility to eliminate one or more ns. Four ns can be part of cycle (turn), but such cycle might not eliminate anything. I'm not certain, but I think this can replace all wings and fishes. I'm not sure if this helps, but I'll try: A symmetric cycle like this: /\ \/ does not eliminate anything (n=1) _x,1_ 1_,_x x_,_1 _1,x_ Non symmetric eliminates // \/ _1,_x x_,1_ 1_,_x _x,x_ Should have L somewhere, because this eliminates all 1s from bottom right.
@riverach179 5 жыл бұрын
I found that I wasn't getting the right configuration very often, but I realised that with two candidates you can guess the third (until you find the right square), and then proceed. Excellent fun.
@rodcastello7780 4 жыл бұрын
Sudoku is all about logically inching our way forward. Having one more tool to get there is very helpful. Thanks. Yes, find a way to make your cursor into a red circle. Just googled this search term and got quite a few results. "red circle mouse pointer"
@muddrosal8065 5 жыл бұрын
I have been using this method for years. I didn't assume it was anything special as it just seemed necessary for the stubborn boards I played. The company I work at developed a sudoku game that had very little regard for setting up a board, so quite a number of the randomly generated puzzles required unorthodox methods to solve. This is a more refined version of my brute force technique, as the rule of 3 evenly divided boxes produces reliable groupings to work from, as opposed to me just running the gauntlet of pencil marks trying to find when I can eliminate a mark or two.
@stefanf922 5 жыл бұрын
I've used this intuitively, somewhat. It can get quite mentally taxing to keep track of yourself.
@2236UmbrellaCorp 5 жыл бұрын
This is some great stuff.
@tiotito31 5 жыл бұрын
I feel like I've seen or heard of something similar, referring to On/Off switches. Which this is just kind of what you're doing. Pick one and see where it takes you and if it works.
@KyleWidmyer 5 жыл бұрын
Ive been using this for years.
@jons2cool1 5 жыл бұрын
So what I'm understanding from this is that it's a technique to identify useful multi-coloring chains? I had a discussion with someone on reddit the other day where they used a technique similar to this, but they did a type of digit forcing chain using a multi-coloring strategy. By assuming the digit is on or off and see if it provides the same value in a certain cell, that could be an extension of this strategy.
@RGS61 2 жыл бұрын
Does the elimination of the "elbow digit" only hold true when two passes through the puzzle, alternating the start from a box containing only two digits, both produce a valid result .. or does simply the existence of three possibilities in a box (in a "slot machine situation") mean that the elbow digit can 'always' be eliminated?
@ChilliDuck 4 жыл бұрын
took me 20 mins. I spotted something in the 1s, and then the 5s, so it seems I found the swordfish and that xcycle lol. but hands down, its only due to the optical enhancements your app is giving me. I can mark places and then just need to follow my mouse. It took my quite some time to actually get used to solve without those helps tbh (because I learned with an app thats giving those enhancements)
@ChilliDuck 4 жыл бұрын
so that method of solving is only really possible when using a app that helps you ig, because I did the same before. eg just make a chain when there are only 2 possiblities and you often can rule out pencilmarks like that. for those 1s at 14:10 you couldve just row 2 column 5 and see that raw 4 column 5 is never a 1. but that type of solving is no fun and only really possible when using a computer because youd need too many pencilmarks imo. its much more elegant and fun to stick to your way of solving trying to notice patterns, instead of brute forcing it tbh
@jilliankratish4651 5 жыл бұрын
For your sudoku solver, could we get 2 additional colors besides black and white? White is nice for resetting a color, but won't help a square stand out from the non-colored ones. And black blocks the numbers inside.
@Socrates... 5 жыл бұрын
Is there a correlation between this and knight's tour in a knights move type puzzle, where a tour could find all potential numbers ?
@malingeorgiev2962 5 жыл бұрын
Well done for Derek! :)
@stephenmccarthy1795 2 жыл бұрын
The”Elbow“ cells share both a row and column with the other two candidates in the box, so whether it is a row or column that gets eliminated in a box, it will be eliminated with the other cell.
@DOHandDOH 5 жыл бұрын
This is basically how I've been doing this for years. I didn't even know there was something peculiar about this technique...
@muddrosal8065 5 жыл бұрын
same boat :)
@danpowell806 5 жыл бұрын
That's just a refinement on postulating a value in a cell and finding a contradiction from that postulate, by identifying a simple heuristic for when that process is much more likely to bear fruit in the form of eliminating possibilities. The reason it's always the 'elbows' that are impossible is that if neither of the starting postulates completes the loop without forming a contradiction or ambiguity, you can narrow e.g. the 2's to one of those two solutions, but no further; for a value in one of those two possibilities to share a row or column with a value in the same box of the other possibility would allow you to rule in that row or column in that box, ruling it out of the other box in that row or column, which means you would have already gotten a number!
@PMA65537 4 жыл бұрын
Picking either 5 in the bottom row leads to deductions that overlap so the 5 in row 9 is found true either way and that is a suitable first move.
@jiminatorx 5 жыл бұрын
Its a fairly simple technique although it can be much more complex than what you are showing. 3 filled on different squares is the simplest and probably most reliable method to check, however you may have 5 and if it leaves a 2x2 block that can be a candidate. There are many other possible versions. The main thing to check is if the exclusions can go around the entire candidate blocks or if they actually loop in a "spiral" pattern with a specific beginning and a specific end which are in a line. You can't do anything with these aside from comparing against other number sets for interactions. To evaluate you are looking for binary candidates, either in a row square or column. The test is for one then the other. As you describe you will often drop "elbows" but much more common is to find that pairs in a square will be in a line which then forces a pair in an adjacent block. Personally I am not that clever with sudoku puzzles, I do the basics, pair interactions, then this technique and then strategic binary guess testing. Just the latter can take some time. All that other stuff just blows my mind.
@NjniaVanDerWald 5 жыл бұрын
Dr Derek has a nice tone to it, doesn't it? Like there is a certain symmetrie inside the structure of that name.
@mickwoolley8267 3 жыл бұрын
So, here is a question. Suppose we get further into the puzzle and now have four 5's say. Three make the slot machine magic triangle. I assume it is still fine to do the same activity and see what drops out isn't it? Also, what is the proof that, if you have two OK paths, the elbows where they join can be eliminated, I can't see why that is valid.
@JayHendren 4 жыл бұрын
This technique almost always ends up being equivalent to a fish or fish-like technique such as X-wing, Swordfish, Finned X-wing, Skyscraper, etc. I've been using it for a while, but I call it a "cycle". As soon as I see a "cycle"/"slot machine", I'll look for a fish first and fall back to the cycle/slot machine if I don't spot any obvious fish right away.
@schizophrenicenthusiast 5 жыл бұрын
The puzzle itself isn't too difficult other than the start. After using the slot machine method to fill out 5s and 1s, it gets quite easy.
@moocowpong1 4 жыл бұрын
Obviously I'm late to the party here, but I wanted to point out that the swordfish the solver finds is actually a red herring - if you tell it to ignore swordfish, it will find the same X-cycle first and then the rest of the puzzle will solve itself with only elementary strategies.
@tzisorey 5 жыл бұрын
Ever thought of doing a video on the process of manual puzzle _setting?_
@hotonis 5 жыл бұрын
Tzisorey Tigerwuf that would be awesome!
@G.Aaron.Fisher 5 жыл бұрын
Information on puzzle setting tends to be the most extremely guarded kind of trade secret. In most cases, the puzzle setter's livelihood depends on their skills and knowledge being somewhat exclusive. So as cool as it would be to see that video, I'm not even sure how they could go about researching it.
@tzisorey 5 жыл бұрын
@@G.Aaron.Fisher Well, there's always just letting a computer create them. :le sigh:
@tzisorey 5 жыл бұрын
@@G.Aaron.Fisher Hopefully they can do something - it'd be fascinating, and having more people able to create unique and interesting puzzles is a good thing. I realise they may want to protect their income and the like, but like CinemaWins says - "I could read every book on neuroscience there is, and I'll _still_ kill everyone whose brain I touch"
@hotonis 5 жыл бұрын
@Aaron Fisher it’s possible that they could discuss some of the more dated setting techniques. Also they could talk a bit about the mindset and what goes into setting a specific puzzle that one of them made. Just getting to see the process of making a puzzle would be extremely interesting. Or they could make a puzzle, have us solve it then do a video of them making it on Patreon.
@LaunaLove 5 жыл бұрын
I've been doing the elimination thing forever, I thought I was cheating at the puzzle cause I'm not an advanced soduko player lol it's awesome to see it being used and not considered "cheating"
5 жыл бұрын
I've tried the puzzle before watching the video and ended up with some pencilmarks, but no progress. Thanks for sharing this method..., but i think there was never, never, never a puzzle like this on the channel, in terms of difficulty. So at this level i would give up...
@ExodaCrown 5 жыл бұрын
That is a neat strategy, I will have to use it on some puzzles. I am curious if doing some light work on the puzzle first affects the strategy? Also, if you test both circuits with only one of them working, does that mean you figured it out for that number? I am rewatching it to see if I missed if that was answered, but from what I know if the one you try doesn't complete it, then that one is wrong. So you get the other one as the correct answer.
@paulstelian97 5 жыл бұрын
If one of the circuits doesn't work you eliminate that clue. Then you may end up with a naked/hidden single in the same box (if you don't then you gain almost nothing)
@danpowell806 5 жыл бұрын
If you start in a box where you have already ruled out all but two cells, (because the others conflict with the given cells) and rule out one more because it causes a contradiction, you can fill in that last possibility.
@Supremebubble 5 жыл бұрын
I'm not even into sudokus but this looks really fun :o I think somewhen in the future I'll prove the correctness of this method just for fun in my free time.
@BillySkceuk 5 жыл бұрын
Cool I got the technique myself before watching (albeit very slowly)
@YahkoKun 5 жыл бұрын
I somewhat came to that technique myself as well but its so time consuming because I essentially fill in all possible pairs for all the numbers across the puzzle. Then I watch if there are locked pairs - in our case in this puzzle its a 1 and 4 in R3/C2 then I simply try to use either 1 and see where it leads me or a 4 and see where it leads me. Then I fishout any squares that have a 3 option and try narrowing it down to 2 sometimes with a 4 option i'm able to eliminate it to a 3 option.
@CGagnon5 5 жыл бұрын
Does everyone not already do this trick? I always considered this a pretty basic technique
@Kiroshima-Official 5 жыл бұрын
My thought exactly. This is literally how I solve even easy sudokus.... Not brand new at all.
@gizmoguyar 5 жыл бұрын
Yeah, I thought this too. I consider this "first level deep." After all direct contradictions have been found you have to start guessing which will lead to more contradictions. Three levels deep is not uncommon for me. I.e. you've made three assumptions before you find a contradiction.
@taylorfisdboss5200 5 жыл бұрын
being able to notate and see all of this at once (because you have to take into account sometimes multiple hypothetical boards) seems somewhat difficult. especially when noticing the squares at 8:41 that are used in neither solution. I am not sure how I would go about notating this in paper especially, and i am not a strong enough solver to keep all of these things in my head at the moment. any ideas on how to easily notate these methods?
@danpowell806 5 жыл бұрын
When working on paper, use the space outside of the puzzle to draw out the cycles and eliminate them; once you are certain that you can eliminate a number from a cell, note it in that cell with a slash through it.
@SeithonJetter 5 жыл бұрын
Huh... weird as it sounds, when i was in college tooling about, I took the same approach to making a sodoku solver lol. never quite got it working but eh nifty to see someone actually got it functional :D