Sudoku Tutorial #21-A / Unique Rectangles Review
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- Опубликовано: 27 окт 2024
- A Complete Review of Tutorials #20 & #21, featuring many additional examples of UR's Type 1 thru 7. UR's are one of the most commonly occurring of all the known solving techniques.
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Swami, I'm a little embarrassed to Admit it but I had to watch your lessons on unique rectangles four times before they really became a part of my solving technique. I've watched all of the people on RUclips and they're not bad but you're patience and the clarity of your instructions are the reason I'm becoming a better solver. Unique rectangles are now a major tool I use. You don't know me but I count your videos to get me out of tight spots in any puzzle. Thanks for your help!!
Richard Vanderpool
Hi Richard. Don't be embarrassed. EVERYBODY would do well to watch all my Lessons 4 times each! I always try to do my best to explain everything clearly, but this is not simple stuff. Some of the techniques take a little while to wrap your head around. Unique Rectangles are VERY common, and you can usually find one or two of them in almost ANY puzzle. So I am glad to hear that you understand them now. Good luck! And if you ever have any questions, please let me know. sudokuswami@gmail.com
Ho
Excellent review. I like how you powered through many examples of the different types of unique rectangles. Thanks for all the informative videos!
so different from 'the explaining them basics',
Great tutorial. I keep coming back to this as a refresher.
The Unique Rectangles have been very precisely and clearly explained to differentiate between their types.
Aneja
Great videos! There are enough different kind of examples to understand, and it is also easy to practice with your video by pausing it and trying yourself. 👍
Thank you for the great video. And as usual nice and productive information!
Thanks for your nice words and continued support, Mirek. I really appreciate it. Much more to come! :-))
Please visit sudokuswami.com for an Outline of the Complete Course, and news about upcoming new Videos..
Sudoku Swami Your channel is one of the best sudoku tutorial channel on YT👍 Hope you can teach us "w wing" and "WXYZ wing" ASAP, these two techniques really confuse me a lot, and they have so many variety type.
Thank you for your comment. I will be covering W-Wings very soon. It will be Tutorial #25. I will cover WXYZ-Wings in my Advanced Series, which will come after the Complete Course is finished. Good luck, and thanks for watching. :-))
You are excellent. Thanks!
Great review!!! 🏆
Swami, I got a little confused on when to treat it as a type 3 versus 4. In one case you look at the non diagonal 2 cells with extra candidates and look at the extra candidates as a virtual pair or set, in the other you look at the non extra candidates and look for one of those out side that can see both. Is there ever a case where it is both a type 3 and 4 and you have to pick which one to take action on because it will destroy the other scenario? Love the videos.
Always analyze it as a Type 4 first. Then if there are no eliminations to be made, check for Type 3. Type 3's are very rare. I cannot recall a puzzle where there were eliminations from a Type 3 and a Type 4 simultaneously, but I suppose it could be possible. If it ever happens, you could make the eliminations from both scenarios. Just go back and get them all. One would not "destroy" the other.
Good job I find all by myself before you explain I am pro because the hodoku program is good, you chose the technique you like exemple :unique rectangle type 1 and Hodoku give this to you and I love this, I can't wait for the BUG+1 and I learn this long time ago
Great!!
Excellent video. Avoid the forbidden pattern!
Swami, Thanks for these videos. I've been studying them for about 4 months and by now I'm a borderline expert. I've solved all the sudoku's I've attempted. This question is about type 4 URs. I'm using the example from 10:24 to 11:48. If there had been a 9 in block 9, would that have resulted in no eliminations? I.e., the 9 would have negated the 5s in row 7? I think the answer is yes but I'm not sure. Thanks again.
I there was a Candidate 9 in R7C8, then there would be no eliminations. It would not qualify as a UR Type 4. Rule 4 applies when only ONE of the Candidates appears outside the two adjacent UR Cells,
@@SudokuSwami Thank you Swami!
This is valuable for sudokus which have a unique solution, but if you are setting up a sudoku, you cannot rely on unique rectangles to be true.
Your videos covered what i needed/wanted to find (which I spent all day locating them). I think you need to be even more clear as to why these rules work, rather than here is the rule and this is what you do. Blindly following a rule is ok, but to understand the reasoning of the method OF THAT rule is something else.
I am also a person with two sight impairments. Highlights in yellow have been hard to follow. Simply because they are low contrast against the white. Do you have PDF document that lists these 7 rules as a reference document?.
If you watch all three UR Videos (#20, #21 & #21-A), and if you pay attention to all the diagrams and listen to everything I say, you will see that I DID explain "why" these techniques work. With all due respect, my Tutorials are available to everyone for free. They require a lot of time and effort on my part. If you want a written list of the Rules, I suggest you get a pad and a pencil, and take some initiative on your own, and write them out. All the information is contained in the Videos.
Nice video, this was good for me to practice these to see whether I could find them myself and make the correct deductions. Some of them I found the whole thing by myself, others I let you find the UR and simply challenged myself to make the correct deductions. I like being given the time to do that (like in this video) as opposed to just simply loading the example with the UR cells already highlighed.
Change of topic but would it be possible for me to send you a puzzle that I had partiular difficulty with (I needed to use the hint button 3 times) spotting the moves required to solve it. I can confirm that the puzzle is solvable with techniques that you've taught or are about to teach very soon. Perhaps this could be for your next random tips / tricks video if you feel your audience would learn a lot from it. At the same time may I contact you about what software you use, I currently use EnjoySudoku app on android, but I can't do stuff like drawing lines (I can do colouring though with up to 2 colours).
First, you can stop the Video, immediately when I put a new puzzle example up, before I start talking about it and highlighting what is going on. That way, you can try to find the related patterns yourself.
Second, yes you can send a puzzle to sudokuswami@gmail.com, and I will analyze it for you.
Third, I draw the lines and arrows with a Program that is OVERLAID on the Sudoku Grid. When you write to me, I will tell you all about it.
@@SudokuSwami 4cs
You cannot have extra candidates in 2 different block because it will cause a 4 block UR and it is forbiden...?
I do not understand your question. The four Cells of ANY UR Pattern must lie in exactly 2 Rows, 2 Columns and 2 Blocks. If the four Cells lie in four Blocks, then it is NOT forbidden, and it is perfectly legal, thus the UR Rules DO NOT apply.
@@SudokuSwami Sorry for my poor english but you cannot have extra candidates in two different block because it would force a 4 block pattern with the other 2 cells and you said that every type of UR must lie in only 2 block.
I am very sorry, but I do not understand what you are trying to say. If you want me to comment further on this, please send me an email containing a diagram that displays what you are talking about. sudokuswami@gmail.com
@@SudokuSwami It must lie in the chute also or it could cause that 4 block pattern...
I'm not sure I've understood the difference between type 3 and 4...
Swami, with respect to type 4 & the last example, if you could not in fact eliminate either of the ER's, could you using the same type 4 method eliminate one of the non-UR's from the unique rectangle if one is a con. pair-- that is, eliminate the non-unique candidate that is also appears in a row, column or the block?
Thank you!!
Hello Charles. ER = Empty Rectangle. UR = Unique Rectangle. I'm very sorry, but I do not understand your question. Also, this Lesson is about Unique Rectangles (not Empty Rectangles). In the example you are referring to (the last example of UR Type 4 at 13:30 to 14:30, either R5C7 or R5C9 MUST be a 4, because they are the only two 4's in Block 6. Therefore, the 6's in those same two Cells MUST be False, otherwise you would have the Forbidden UR Pattern, which is impossible in a puzzle with only one unique solution. Good luck. :-))
Hi Swami,
Festive greetings to you. Hope all is well on your side.
I'm still Sokuko-ing and have recently reverted to logic solving (minimal notation). Puzzles attempted are generally easier, but I feel this approach gives the grey matter a good, but different sort of workout to full-notation techniques.
The other day, I encountered an interesting puzzle, which had me convinced it was invalid. It gave a UR in 6 and 7 ( final solution had 6 at two opposite corners and 7 at the other corners) Surely this was wrong!?. I then realised that the two 7s were actually originally given values and the 6s solved for. Clearly this validates the puzzle, but does it mean one needs to take greater care when applying UR logic?
Here are two important rules to remember: 1.) The four Cells of any UR Pattern cannot contain any Givens. They must all be unsolved Cells to begin with. 2.) The four Cells must lie in exactly two Rows, two Columns, and two Blocks. They cannot lie in FOUR Blocks. Follow these two rules, and you won't go wrong.
thank youu!
How to make the difference with extra candidates type 3 with extra candidate type 4 ?
Type 3 deals with Virtual Subsets, and the eliminations occur OUTSIDE the UR Cells. Type 4 deals with a Conjugate Pair on one of the UR Candidates allowing you to eliminate the OTHER UR Candidate from the UR Cells themselves. These two methods are entirely different. Please watch Tutorial #20 for a full explanation of Type 4, and Tutorial #21 for a full explanation of Type 3.
You must be a professor to explain things the way you are doing!
12:28 What if all yellow cells would 3/9? It still in an exceptional case doesn't work Unique Rectangle?
It means: if all yellow cells in four boxes contain only 3/9, then we have a Deadly Pattern or not necessarily?
It would be possible to have 3 & 9 in all four of those Yellow Cells, but NOT in this puzzle. The presence of the Bi-Value Cell R8C3, (also containing 3 & 9), PREVENT R8C1 & R8C9 from BOTH being BVC's of 3 & 9! You would then have THREE BVCs with 3 & 9 in the same House (Row 8), which is impossible. But if R8C3 contained ADDITIONAL Candidates, and was NOT a BVC, then YES, the four Yellow Cells could all contain 3 & 9, and it would NOT comprise the Forbidden Pattern, because the four Cells lie in four separate Blocks. A UR Pattern must lie in exactly Two Rows, Two Columns, and Two Blocks. :-))
I thought so :-) I visualized myself a similar problem on the rows(columns) and I saw that two houses rule must be (2 rows/2 colums/ 2 blocks). Otherwise are created permutations which never different solutions anytime. However, it's the hardest to visualize on 4 blocks :-))
Right. If you had four identical BVCs like that, in four Blocks, it would simply be 4 sets of Naked Pairs, or a group of Remote Pairs, and there would be no problem with that.
Let me say this way: If neither of the 4's or 6's (the "URs") were in fact conjugate pairs, could you use UR Type 4 method to eliminate one of the 2 non-URs ( 2 or 3) in the rectangle block 6 if one is a conjugate pair ??
No, Charles. What you have described is NOT a UR Type 4. And you could NOT eliminate the 2 or the 3. A UR Type 4 can ONLY be used to eliminate ONE of the UR Candidates, but only if that Candidate appears OUTSIDE of the two non-diagonal UR Cells, and the other UR Candidate does not. It has no bearing on the additional Candidates.
Good luck! :-))
Meant to say "non-ER" & not "non-unique."
How r u sir
For a guy who wears black, sunglasses, and long hair, you're a pretty big nerd. ;)