Dear swami ji, I would like to know where to go to see your advance technique which you had mentioned several times in your videos. I want to learn WXYZ rule.
Dear Swami, I hope that you can consider doing a tutorial on APE because that technique uses ALS too. It’s only when I viewed this video that I fully understood SDC. You’re a teacher extraordinaire- never leaving any stone unturned. More power to you. As usual I’m a big fan of yours.
Is this Baby-Rey from the Sudoku Forum? Or someone else? APE is a very rare configuration, and very difficult to find, even when they ARE there. If I produce an Advanced Series of Tutorials someday, I will include the APE Technique. But it will not be included in my Complete Course. Likewise for ALS & 3-D Medusa, etc. Cheers! And thanks for your support! Good luck!
Sudoku Swami yes sir, baby -rey is my fb name because my husband and myself use only one fb account. Thanks for the reply. Let me take this opportunity again to thank you for AIC II. It really helped me a lot in solving diabolical and extreme puzzles. There are times it will take me days doing these chains but I know that I did it and did not make short cuts or resort to bowman’s bingo.
Fantastic! The next three Videos in my Complete Course will focus entirely on the various configurations for AICs Type II. These will be Tutorials #35, #36 & #37. Stay tuned! And good luck! :-))
Hi Adelina, If you're seeking to understand ALS and APE just to broaden your knowledge, that's great. But if you're simply seeking to conquer puzzles that have those structures, my personal experience is that a great deal of these puzzles can also be solved with chains (SDCs included). I find chain construction to be a much more repeatable way of solving such puzzles as opposed to spending hours looking for structures that in all likelihood do not even exist. Then again, maybe another excellent Swami tutorial on those techniques may change my mind on this.
Hey Brad, good to hear from you. I could not agree with you more about APE & ALS. These are great concepts to know, and can be helpful in certain rare situations, but the vast majority of all puzzles (most probably ANY puzzle) can be solved without them. Whether I make any Videos dealing with these two concepts, will depend on the demand for it. In any event, be well & be happy, my old friend. :-))
It IS an esoteric and complicated technique! Ha-ha. But that does not mean it cannot be understood and mastered. Understanding WHY it works, is the key.
SDC can also be viewed as a special case of ALS-XZ rule while x could also be just used as z to eliminate cells seeing both x in the two related ALS found.
Ha ha. Yes, SDC's are powerful. They are sometimes not very easy to see. You have to make it a point to look for them. And the best time to do that, is when you are absolutely stuck.
Hi Doron, Must say that after also having a dislike for chains, my view on them has flipped 180 degrees. Much of this is due to the very instructive tutorials posted by Swami. I've been solving a great number of extreme puzzles using chains. But when I say chains, I mean the multi-branching variety. I raised my level on an app where SDCs, APE and ALS often came up. On the odd occasion, I may have spotted these, but more often than not, the structure was only revealed to me after I had become frustrated and requested a hint. I decided I needed something more repeatable. I've pulled my hair out many times after spending hours looking for an SDC only to find the key is an APE structure, or maybe even something a lot less complex, like a Wing of sorts. I decided to master chains (at least in my own mind) and since then, I've been solving the same difficulty of puzzle without ever seeking any of those exotic/esoteric structures. By the law of averages, an extremely small number of puzzles may contain one or more of the structures I refer to, and sequentially seeking these is frustratingly time consuming, with the knowledge that in all probability they do not even exist in the puzzle. On the other hand, each and every puzzle WILL have plenty of chains...
Hi Swami, thank you for adding next technic to my repertoire. Of course it needs to be training but knowing that this exist and how works is great advnatage.As usually well explained!
Sue must've been a genius. Down here in Cape Town, I had a neighbor, Susan de Kok (It's an Afrikaans name), but somehow, I can't see her coming up with something like this. I'm grappling with understanding the logic, but once located, applying it looks simple. I had a Math teacher, God bless him, who always emphasized, it's great to know "The How" part, but mastering "The Why" part takes you so much further. Given my dislike for searching for subsets, and my perception that these things look a bit like subsets on steroids, it's a pretty intimidating technique. Still, an excellent instructional video Sensei .......er Swami. Many thanks, and I'm definitely going to make a conscious effort to look for these..
Susan de Kok. How funny!! I think the original Sue de Coq is actually a man, but I'm not 100% sure about that. Sue, if you're out there, please let us know!! Cape Town....wow. I've been to Johannesburg a couple of times but never to Cape Town. I hear it's nice.
Interesting to hear you've visited our shores. You have an outdoorsy look about you, so I'm wondering if your visit was to experience the wildlife? As a born and bred Capetonian, my premise of my hometown being the best place in the country is obviously biased. But I know it has over the years developed into a popular tourist destination. Current state of affairs is however not so good, so maybe not recommended at this time.
I did go to some big game preserves while I was there, but the purpose of my visit was to play a series of concerts at nearby Sun City, back in the 1980's.
I think there is a general rule that applies to SDC and possibly other patterns too. It goes something like this: If there exists a set of “n” candidates in “n” cells, the "n" candidates are essentially locked within those cells. In that case, any candidate “x” outside the set must be false if it sees all candidate “x” within the set. It isn't necessary for the candidate "x" outside the set to see all cells in the set. It only needs to see all candidates "x" within the set to be false. It’s logical, and easy to say, but not so easy to spot in a puzzle. That said, there is usually a big payoff when you do, so, it's worth it to keep looking.
Nice try, but your definition applies in some cases, but not in ALL cases, and therefore it must be thrown out as invalid and fallacious. You need to add more restrictions. Consider these three Cells: R3C3, R1C9, & R7C7. Now imagine that the Candidates 1-2-3 appear in all three of those Cells. This would qualify as a "set" according to your definition. Three Candidates in three Cells. Now consider the Cell R3C7. This Cell can see all three of the Cells in the Set. However, in this configuration, the Set does not preclude a 1, 2 or 3 from being True in R3C7. Capisce? Here is the correct definition, taken from the Inventor of this technique: Consider the set of unfilled cells C that lies at the intersection of Box B and Row (or Column) R. Suppose |C|>=2. Let V be the set of candidate values to occur in C. Suppose |V|>=|C|+2. The pattern requires that we find |V|-|C|+n cells in B and R, with at least one cell in each, with at least |V|-|C| candidates drawn from V and with n the number of candidates not drawn from V. Label the sets of cells CB and CR and their candidates VB and VR. Crucially, no candidate from V is allowed to appear in VB and VR. Then C must contain V\(VB U VR) [possibly empty], |VB|-|CB| elements of VB and |VR|-|CR| elements of VR. The construction allows us to eliminate candidates VB U (V\VR) from B\(C U CB), and candidates VR U (V\VB) from R\(C U CR).
I'm studying systematically Almost Locked Set method to be able to solve more and more difficult puzzle. And I have to say that Sue De Coq convinces me very well. SDC appears less often than ALS, but I'm starting from Sue De Coq successfully :) It fits to my style of solving - capture many naked sets (pairs, triples, quads) and trying some connection between COLUMNS/ROWS and BOXES. In case of Sue De Coq even naked quints on the crossroad column/rows and boxes if only makes a logical consequences :)
Good work. I hope to cover various configurations of ALS sometime in the future. But right now, I have to finish my Complete Course. Tutorial #35 is coming soon.... Good luck! :-))
SDC is an Almost Almost Locked Set (AALS) 4 candidates in just 2 cells or 5 candidates in just 3 cells. Its name is derived by its first discoverer Sue de Coq.
I have understood the principles but now I really need to practice to see if I could really solve the sudoku. I have copied all types 1and 2 and solve them myself. Of course I f in doubt can go back to swami ji.👍
Hello, I am an almost 3 months old rookie and I´d like to know the steps/ sheme to find these 2 types of the fascinating technique.... Which one should I search the first then go on??? Thank you so much!!!....
No problem. I understand. I was not offended at all. I thought it was funny. I am impressed that you can speak four languages. I can barely speak two! I am glad to hear that you understand the SDC technique..
Actually, for me, it is one of the easiest techniques to grasp. It is just an extension of the subset techniques. And you did an excellent job explaining it to boot!
Swami how do you go about recognising an SDC? Do you first find different BVCs for example. I am having difficulty finding them or is it another case of practice makes perfect?
Hello Kay. Well, of course, practicing is always the the path to improvement. But the best way to identify SDC's in puzzles is to simply look for their inherent characteristics. Remember, I only covered the two most basic types of SDC's in this Tutorial. There are many other forms these things can take, including various extended versions, which I plan to cover in my Advanced Series. But with the two most basic types, you should look for either 4 Candidates in 2 Cells, or 5 Candidates in 3 Cells, with those 2 or 3 Cells lying in the intersection of a Row and a Block, or the intersection of a Column and a Block. Once you find either of those situations, you are on your way. Then you must find another Cell in the Row or Column, outside the Block, and another Cell within the Block, not in the Row or Column, each containing Candidates taken from the Intersection Cells, but that are different from each other. If this sounds confusing, then you should watch the Video again. Even though you may find an SDC at any time during the solving of a puzzle, the best time to look for one, is when you have exhausted all the simpler techniques, and you are absolutely stuck. Then just go through the 9 Blocks, one at a time, without using Candidate Filters, and look for a 2-Cell or a 3-Cell Intersection containing the qualifying # of Candidates. Good luck. :-))
Thank you for your detailed reply. I have watched the video several times and I get it! I still find it testing to spot them. I have turned on 'Practice' on the app and am getting better by using your methodical approach.
In SDC Type 1, if one (or 2) of two intersection cells has only 2 candidates out of 4 and one of each block cell and row cells are those 2 numbers, then that 2 candidate intersection cell is turned out to be empty. In that case, is this SDC technique still working? I might be wrong, though, but hard to visualize. I always appreciated your excellent work.
I am reluctant to answer your question, until I am 100% sure I understand what you are asking. Please send a diagram to sudokuswami@gmail.com and I will be happy to analyze it for you.
Sorry for the confusion. Let me explain from your 2nd example (at 24:11). One of intersection cell R7C5 has only 2 numbers, 3 & 7. If row cell, R7C2 is 7 and the block cell, R8C6 is 3, then that intersection cell R7C5 turns out to be empty. But those two intersection cells should be 15 pairs to be SDC. I’m just wondering how it’s assured that that empty cell R7C5 has 1 or 5. I hope this is clear to you.
It is not true that the two intersection Cells in this example must be a {1,5} Naked Pair. It is NOT a prerequisite. The main concept to remember, is that the four Cells act as a dis-jointed Quad. The four Cells together must be solved for {1,3,5,7} in some unknown order. If R7C2 is solved for 7, then R7C5 must be solved for 3, and R8C6 must be solved for 1, leaving 5 as the solution to R7C4. If you end up with an empty Cell, you have either made a mistake, or your puzzle is invalid.
I think you were confused from some of the hand-drawn examples, where the intersection Cells turned out to be a Naked Pair. But this is only the case, when each Intersection Cell contains ALL FOUR of the Candidates. The Candidates are not always distributed perfectly like that, but the SDC will still work as a dis-jointed Quad.
Thank you so much for your detailed explanation, Master Swami. I was confused in the beginning but now I’m clear. My original supposition was NOT correct. If the row cell R7C2 is 7, then block cell R8C6 cannot be assumed as 3 because one of intersection cell R7C5 should be 3 by virtue of BVC. Sorry for asking this confusing question, though. I really appreciated your help and excellent work.
The Cells of a Locked Set must all lie within a Single House (except in cases of APE and Sue de Coq, for example, which are essentially broken sets). The Cells you denote DO NOT lie in the same House, and do not represent a Locked Set. You are correct that Cell R6C7 is eventually solved for 4, but this cannot be deduced at this point in the puzzle, based on the 5 Cells you named.
Hello Thore. Thank you for your continued support. The SK Loop is somewhat of an esoteric pattern, and it is my opinion that it would appeal to a very small but sophisticated group of Sudoku fans. I intend to resume Video production sometime later this year, but I have at least 40 Videos planned before I would ever consider doing a Video on the SK Loop. When I finally get to my Advanced Series, I may do a Video on SK Loops, but it would only be after I do several other Videos on more common Patterns. Good luck! SS
Yes, it is! And I only covered the two most Basic Types in this Tutorial. When I cover all the extended versions and variations in my Advanced Series, you will be blown away by how versatile and powerful they really are. Thank you for your comment.
Yes, it is a slight variation of exactly the same thing. Both are Subsets (or Locked Sets) that lie in Cells that are not confined to just ONE House. They are broken up into two Houses. But it is still N # of Candidates in N # of Cells. The eliminations depend on which Candidates and which Cells can see each other.
Hi Swami, I have understood the logic of the basic SDC's okay. However when it comes to the extended types, that is where things get extremely complicated for me. This website (www.taupierbw.be/SudokuCoach/SC_SuedecoqExtended.shtml) shows two examples of extended SDCs that I'm having trouble wrapping my head around what's going on with them. So how would you find these in an actual puzzle and know whether or not it's valid?
Cannot open your link. The most important thing to remember, is that the total # of Candidates must equal the total # of Cells. It acts like a 'broken" Subset. Every time you add another Candidate to the formation, you must also add another Cell.
@@SudokuSwami Ok. You mentioned here that the extended types are better saved for another tutorial. When is your advanced series going to become available?
Due to personal reasons, my Video Production is on hold indefinitely. If and when I ever resume production, I will post an alert for all the Subscribers to this Channel.
Hello Mourad. This Sudoku Course is a work in progress. If you visit sudokuswami.com you will find an Outline of the Course, and you can also see which Videos I am currently working on. Video #27 has not been completed yet. I am going as fast as I can.
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Dear swami ji, I would like to know where to go to see your advance technique which you had mentioned several times in your videos. I want to learn WXYZ rule.
Please visit sudokuswami.com for more info and news about upcoming Videos!
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Kudos to your incredibly comprehensive instruction.
Thank you so much ! Your explanations are very clear and, thanks to your excellent prononciation, I can understand very well :-) Thank you !
I must see this lesson a few more times to remember what to look for.
Enjoyed thoroughly .you explain every rule very well.
you made me love sudoku for your amazing videos thanks soooooo much SIR
Dear Swami, I hope that you can consider doing a tutorial on APE because that technique uses ALS too. It’s only when I viewed this video that I fully understood SDC. You’re a teacher extraordinaire- never leaving any stone unturned. More power to you. As usual I’m a big fan of yours.
Is this Baby-Rey from the Sudoku Forum? Or someone else? APE is a very rare configuration, and very difficult to find, even when they ARE there. If I produce an Advanced Series of Tutorials someday, I will include the APE Technique. But it will not be included in my Complete Course. Likewise for ALS & 3-D Medusa, etc. Cheers! And thanks for your support! Good luck!
Sudoku Swami yes sir, baby -rey is my fb name because my husband and myself use only one fb account. Thanks for the reply. Let me take this opportunity again to thank you for AIC II. It really helped me a lot in solving diabolical and extreme puzzles. There are times it will take me days doing these chains but I know that I did it and did not make short cuts or resort to bowman’s bingo.
Fantastic! The next three Videos in my Complete Course will focus entirely on the various configurations for AICs Type II. These will be Tutorials #35, #36 & #37. Stay tuned! And good luck! :-))
Hi Adelina,
If you're seeking to understand ALS and APE just to broaden your knowledge, that's great. But if you're simply seeking to conquer puzzles that have those structures, my personal experience is that a great deal of these puzzles can also be solved with chains (SDCs included). I find chain construction to be a much more repeatable way of solving such puzzles as opposed to spending hours looking for structures that in all likelihood do not even exist.
Then again, maybe another excellent Swami tutorial on those techniques may change my mind on this.
Hey Brad, good to hear from you. I could not agree with you more about APE & ALS. These are great concepts to know, and can be helpful in certain rare situations, but the vast majority of all puzzles (most probably ANY puzzle) can be solved without them. Whether I make any Videos dealing with these two concepts, will depend on the demand for it. In any event, be well & be happy, my old friend. :-))
Great tutorial. Thanks, Swami.
Excellent. I always thought this an esoteric and complicated technique. You completely demystified it, as always.
It IS an esoteric and complicated technique! Ha-ha. But that does not mean it cannot be understood and mastered. Understanding WHY it works, is the key.
Great video. Fascinating that techniques like this exist.
Very interesting. Hard to stuff into my brain. But your presentation is so nicely direct.
Great. Thanks. Welcome aboard. :-))
Very good. By it, I was successful with a sudoku very difficult.
Thanks.
SDC can also be viewed as a special case of ALS-XZ rule while x could also be just used as z to eliminate cells seeing both x in the two related ALS found.
Thanks Swami, for adding yet another technique to my arsenal! Just got to find one of the jolly things now! Haha!
This SDC thing is realy amazing.
(Evrything that can help me avoid looking for those chains is wellcome...)
Ha ha. Yes, SDC's are powerful. They are sometimes not very easy to see. You have to make it a point to look for them. And the best time to do that, is when you are absolutely stuck.
Hi Doron,
Must say that after also having a dislike for chains, my view on them has flipped 180 degrees. Much of this is due to the very instructive tutorials posted by Swami. I've been solving a great number of extreme puzzles using chains. But when I say chains, I mean the multi-branching variety. I raised my level on an app where SDCs, APE and ALS often came up. On the odd occasion, I may have spotted these, but more often than not, the structure was only revealed to me after I had become frustrated and requested a hint.
I decided I needed something more repeatable. I've pulled my hair out many times after spending hours looking for an SDC only to find the key is an APE structure, or maybe even something a lot less complex, like a Wing of sorts. I decided to master chains (at least in my own mind) and since then, I've been solving the same difficulty of puzzle without ever seeking any of those exotic/esoteric structures. By the law of averages, an extremely small number of puzzles may contain one or more of the structures I refer to, and sequentially seeking these is frustratingly time consuming, with the knowledge that in all probability they do not even exist in the puzzle. On the other hand, each and every puzzle WILL have plenty of chains...
Hi Swami, thank you for adding next technic to my repertoire. Of course it needs to be training but knowing that this exist and how works is great advnatage.As usually well explained!
I always appreciate your comments, Mirek. Thanks for sticking with me.
Sue must've been a genius. Down here in Cape Town, I had a neighbor, Susan de Kok (It's an Afrikaans name), but somehow, I can't see her coming up with something like this.
I'm grappling with understanding the logic, but once located, applying it looks simple. I had a Math teacher, God bless him, who always emphasized, it's great to know "The How" part, but mastering "The Why" part takes you so much further.
Given my dislike for searching for subsets, and my perception that these things look a bit like subsets on steroids, it's a pretty intimidating technique.
Still, an excellent instructional video Sensei .......er Swami. Many thanks, and I'm definitely going to make a conscious effort to look for these..
Susan de Kok. How funny!! I think the original Sue de Coq is actually a man, but I'm not 100% sure about that.
Sue, if you're out there, please let us know!!
Cape Town....wow. I've been to Johannesburg a couple of times but never to Cape Town. I hear it's nice.
Interesting to hear you've visited our shores. You have an outdoorsy look about you, so I'm wondering if your visit was to experience the wildlife?
As a born and bred Capetonian, my premise of my hometown being the best place in the country is obviously biased. But I know it has over the years developed into a popular tourist destination. Current state of affairs is however not so good, so maybe not recommended at this time.
I did go to some big game preserves while I was there, but the purpose of my visit was to play a series of concerts at nearby Sun City, back in the 1980's.
Sue de coq was active in 2005 in forum.enjoysudoku.com. His/her name is very likely to be derived from the similar pronounciation as sudoku.
I think there is a general rule that applies to SDC and possibly other patterns too. It goes something like this:
If there exists a set of “n” candidates in “n” cells, the "n" candidates are essentially locked within those cells. In that case, any candidate “x” outside the set must be false if it sees all candidate “x” within the set. It isn't necessary for the candidate "x" outside the set to see all cells in the set. It only needs to see all candidates "x" within the set to be false.
It’s logical, and easy to say, but not so easy to spot in a puzzle. That said, there is usually a big payoff when you do, so, it's worth it to keep looking.
Nice try, but your definition applies in some cases, but not in ALL cases, and therefore it must be thrown out as invalid and fallacious. You need to add more restrictions. Consider these three Cells: R3C3, R1C9, & R7C7. Now imagine that the Candidates 1-2-3 appear in all three of those Cells. This would qualify as a "set" according to your definition. Three Candidates in three Cells. Now consider the Cell R3C7. This Cell can see all three of the Cells in the Set. However, in this configuration, the Set does not preclude a 1, 2 or 3 from being True in R3C7. Capisce?
Here is the correct definition, taken from the Inventor of this technique:
Consider the set of unfilled cells C that lies at the intersection of Box B and Row (or Column) R. Suppose |C|>=2. Let V be the set of candidate values to occur in C. Suppose |V|>=|C|+2. The pattern requires that we find |V|-|C|+n cells in B and R, with at least one cell in each, with at least |V|-|C| candidates drawn from V and with n the number of candidates not drawn from V. Label the sets of cells CB and CR and their candidates VB and VR. Crucially, no candidate from V is allowed to appear in VB and VR. Then C must contain V\(VB U VR) [possibly empty], |VB|-|CB| elements of VB and |VR|-|CR| elements of VR. The construction allows us to eliminate candidates VB U (V\VR) from B\(C U CB), and candidates VR U (V\VB) from R\(C U CR).
I'm studying systematically Almost Locked Set method to be able to solve more and more difficult puzzle. And I have to say that Sue De Coq convinces me very well. SDC appears less often than ALS, but I'm starting from Sue De Coq successfully :)
It fits to my style of solving - capture many naked sets (pairs, triples, quads) and trying some connection between COLUMNS/ROWS and BOXES. In case of Sue De Coq even naked quints on the crossroad column/rows and boxes if only makes a logical consequences :)
Good work. I hope to cover various configurations of ALS sometime in the future. But right now, I have to finish my Complete Course. Tutorial #35 is coming soon.... Good luck! :-))
SDC is an Almost Almost Locked Set (AALS) 4 candidates in just 2 cells or 5 candidates in just 3 cells. Its name is derived by its first discoverer Sue de Coq.
This one is brilliant.
Beautiful
I have understood the principles but now I really need to practice to see if I could really solve the sudoku. I have copied all types 1and 2 and solve them myself. Of course I f in doubt can go back to swami ji.👍
Wow, i understood this
This is without question, the best Comment I have ever received. Ha ha. Great! LOL
Sue de Coq = Rooster sweat heh, love this technique and your lessons are fantastic. Opening up techniques I would never have tried.
Hello,
I am an almost 3 months old rookie and I´d like to know the steps/ sheme to find these 2 types of the fascinating technique.... Which one should I search the first then go on???
Thank you so much!!!....
finally understand what id sdc🎉
Brilliant. I have a new drag name!
Crystal Clear as usual and thank you for doing the donkey work (the why) for us.
Donkey work? Ha-ha. So now I am a beast of burden? It is my job to show you "the why." :-))
Hi Swami, I do not mean to be disrespectful, English is my distant fourth language:)!
No problem. I understand. I was not offended at all. I thought it was funny. I am impressed that you can speak four languages. I can barely speak two! I am glad to hear that you understand the SDC technique..
Actually, for me, it is one of the easiest techniques to grasp. It is just an extension of the subset techniques. And you did an excellent job explaining it to boot!
Sounds good. Thanks. Good luck!
Swami how do you go about recognising an SDC? Do you first find different BVCs for example. I am having difficulty finding them or is it another case of practice makes perfect?
Hello Kay. Well, of course, practicing is always the the path to improvement. But the best way to identify SDC's in puzzles is to simply look for their inherent characteristics. Remember, I only covered the two most basic types of SDC's in this Tutorial. There are many other forms these things can take, including various extended versions, which I plan to cover in my Advanced Series. But with the two most basic types, you should look for either 4 Candidates in 2 Cells, or 5 Candidates in 3 Cells, with those 2 or 3 Cells lying in the intersection of a Row and a Block, or the intersection of a Column and a Block. Once you find either of those situations, you are on your way. Then you must find another Cell in the Row or Column, outside the Block, and another Cell within the Block, not in the Row or Column, each containing Candidates taken from the Intersection Cells, but that are different from each other. If this sounds confusing, then you should watch the Video again. Even though you may find an SDC at any time during the solving of a puzzle, the best time to look for one, is when you have exhausted all the simpler techniques, and you are absolutely stuck. Then just go through the 9 Blocks, one at a time, without using Candidate Filters, and look for a 2-Cell or a 3-Cell Intersection containing the qualifying # of Candidates. Good luck. :-))
Thank you for your detailed reply. I have watched the video several times and I get it! I still find it testing to spot them. I have turned on 'Practice' on the app and am getting better by using your methodical approach.
Sounds good. Glad to hear it. :-))
In SDC Type 1, if one (or 2) of two intersection cells has only 2 candidates out of 4 and one of each block cell and row cells are those 2 numbers, then that 2 candidate intersection cell is turned out to be empty. In that case, is this SDC technique still working? I might be wrong, though, but hard to visualize. I always appreciated your excellent work.
I am reluctant to answer your question, until I am 100% sure I understand what you are asking. Please send a diagram to sudokuswami@gmail.com and I will be happy to analyze it for you.
Sorry for the confusion. Let me explain from your 2nd example (at 24:11). One of intersection cell R7C5 has only 2 numbers, 3 & 7. If row cell, R7C2 is 7 and the block cell, R8C6 is 3, then that intersection cell R7C5 turns out to be empty. But those two intersection cells should be 15 pairs to be SDC. I’m just wondering how it’s assured that that empty cell R7C5 has 1 or 5. I hope this is clear to you.
It is not true that the two intersection Cells in this example must be a {1,5} Naked Pair. It is NOT a prerequisite. The main concept to remember, is that the four Cells act as a dis-jointed Quad. The four Cells together must be solved for {1,3,5,7} in some unknown order. If R7C2 is solved for 7, then R7C5 must be solved for 3, and R8C6 must be solved for 1, leaving 5 as the solution to R7C4. If you end up with an empty Cell, you have either made a mistake, or your puzzle is invalid.
I think you were confused from some of the hand-drawn examples, where the intersection Cells turned out to be a Naked Pair. But this is only the case, when each Intersection Cell contains ALL FOUR of the Candidates. The Candidates are not always distributed perfectly like that, but the SDC will still work as a dis-jointed Quad.
Thank you so much for your detailed explanation, Master Swami. I was confused in the beginning but now I’m clear. My original supposition was NOT correct. If the row cell R7C2 is 7, then block cell R8C6 cannot be assumed as 3 because one of intersection cell R7C5 should be 3 by virtue of BVC. Sorry for asking this confusing question, though.
I really appreciated your help and excellent work.
If we take F5 ,H5, I5, F6 and D6 we have a locked set of 5 numbers and then we can deduce the 4 on G6 ????
(Sudoku at 35:20)
Please use Rows 1-9 and Columns 1-9, (i.e., R1C1), to express your Cell Notations. Your question does not make any sense to me at Video Time = 35:20
Sorry for my bad notations
My question is do we have a locked set numbers with R5C6,R5C8,R5C9,R6C4,R6C6 ?
So we can eliminate 7 of R6C7 ?
The Cells of a Locked Set must all lie within a Single House (except in cases of APE and Sue de Coq, for example, which are essentially broken sets). The Cells you denote DO NOT lie in the same House, and do not represent a Locked Set. You are correct that Cell R6C7 is eventually solved for 4, but this cannot be deduced at this point in the puzzle, based on the 5 Cells you named.
@@SudokuSwami thank u
Would Swami explain the new SK Loop or Domino Loop?
Hello Thore. Thank you for your continued support. The SK Loop is somewhat of an esoteric pattern, and it is my opinion that it would appeal to a very small but sophisticated group of Sudoku fans. I intend to resume Video production sometime later this year, but I have at least 40 Videos planned before I would ever consider doing a Video on the SK Loop. When I finally get to my Advanced Series, I may do a Video on SK Loops, but it would only be after I do several other Videos on more common Patterns. Good luck! SS
SDC is really powerful!
Yes, it is! And I only covered the two most Basic Types in this Tutorial. When I cover all the extended versions and variations in my Advanced Series, you will be blown away by how versatile and powerful they really are. Thank you for your comment.
Really looking forward to your advanced series. Thanks for your effort!
Interesting ....is it similar to wxyz chain?
I meant wing not chain
Yes, it is a slight variation of exactly the same thing. Both are Subsets (or Locked Sets) that lie in Cells that are not confined to just ONE House. They are broken up into two Houses. But it is still N # of Candidates in N # of Cells. The eliminations depend on which Candidates and which Cells can see each other.
Hi Swami, I have understood the logic of the basic SDC's okay. However when it comes to the extended types, that is where things get extremely complicated for me. This website (www.taupierbw.be/SudokuCoach/SC_SuedecoqExtended.shtml) shows two examples of extended SDCs that I'm having trouble wrapping my head around what's going on with them. So how would you find these in an actual puzzle and know whether or not it's valid?
Cannot open your link. The most important thing to remember, is that the total # of Candidates must equal the total # of Cells. It acts like a 'broken" Subset. Every time you add another Candidate to the formation, you must also add another Cell.
@@SudokuSwami Ok. You mentioned here that the extended types are better saved for another tutorial. When is your advanced series going to become available?
Due to personal reasons, my Video Production is on hold indefinitely. If and when I ever resume production, I will post an alert for all the Subscribers to this Channel.
Somebody can help to find Sudoku Tutorial 27#
Hello Mourad. This Sudoku Course is a work in progress. If you visit sudokuswami.com you will find an Outline of the Course, and you can also see which Videos I am currently working on. Video #27 has not been completed yet. I am going as fast as I can.
Sudoku Swami
Thanks for your fast answer. I appreciate.
Your course is like mathematical courses even if Sudoku has nothing to do with Mathematics
Dude, come on, give it up. You're a mathematician. ;)
Okay. Whatever you say. I'm a mathematician!
My head hurts 😅