The New Sudoku Players' Forum

by **kurbads** » Sat Aug 07, 2021 10:38 am

If I put 8 in R3C5, it creates a deadly pattern.

But I browsed through the rules and did not notice anything resembling it except Sashimi X-Wing. It leads to different exclusions though.

...|.6.|97.
..2|..3|5.1
...|7.5|...
---+---+---
.15|8..|3..
..9|...|8..
..7|..9|14.
---+---+---
...|1.8|...
4.6|5..|7..
.81|.7.|...

Edit: Ha-ha, it could be Sashimi Unique rectangle, type 1. Or Unique trapezoid type 1

Website · by **denis_berthier** » Sat Aug 07, 2021 11:45 am

.
You're missing a few Singles

Hidden Text: Show

Code: Select all: Resolution state after Singles: +-------------+-------------+-------------+ ! 35 35 8 ! 2 6 1 ! 9 7 4 ! ! 9 7 2 ! 4 8 3 ! 5 6 1 ! ! 1 6 4 ! 7 9 5 ! 2 8 3 ! +-------------+-------------+-------------+ ! 6 1 5 ! 8 2 4 ! 3 9 7 ! ! 23 4 9 ! 36 1 7 ! 8 25 256 ! ! 8 23 7 ! 36 5 9 ! 1 4 26 ! +-------------+-------------+-------------+ ! 7 25 3 ! 1 4 8 ! 6 25 9 ! ! 4 9 6 ! 5 3 2 ! 7 1 8 ! ! 25 8 1 ! 9 7 6 ! 4 3 25 ! +-------------+-------------+-------------+

finned-x-wing-in-rows: n2{r9 r6}{c9 c1} ==> r5c1 ≠ 2
stte

by **kurbads** » Sat Aug 07, 2021 11:47 am

Another one.

One of the cells C6R7-9 must be 1 or 4. Together with the other pink cells in the trapezoid they form a deadly pattern unless C4R8 is 5!

Right?

Edit: No, the assumption is wrong, it pretty quickly led to a dead end.

But it has another rectangular but I am not sure if I can make out what it is.

by **kurbads** » Sat Aug 07, 2021 11:55 am

denis_berthier wrote:.
You're missing a few Singles[hidden]naked-single ==> r8c6 = 2
naked-single ==> r7c3 = 3

Sorry, no, I am not missing it. It is black in the image.
The game does not allow copy filled cells.

The text version is of a blank puzzle.

I have a feeling that you do not see the image.

I have attachment limit here so I put it on imgur.com

https://i.imgur.com/e8xp5B4.png

denis_berthier wrote:.
finned-x-wing-in-rows: n2{r9 r6}{c9 c1} ==> r5c1 ≠ 2

Could you put it in words?

Anyway, I solved it differently. And anyway, it is unrelated to question and ignores what is on board.

Copying and pasting the code into an auto-solver does not create value.

Website · by **denis_berthier** » Sat Aug 07, 2021 2:46 pm

kurbads wrote:
denis_berthier wrote:.
You're missing a few Singles[hidden]naked-single ==> r8c6 = 2
naked-single ==> r7c3 = 3

Sorry, no, I am not missing it. It is black in the image.

denis_berthier wrote:.
finned-x-wing-in-rows: n2{r9 r6}{c9 c1} ==> r5c1 ≠ 2

Could you put it in words?
Anyway, I solved it differently. And anyway, it is unrelated to question and ignores what is on board.
Copying and pasting the code into an auto-solver does not create value.

I started from what you wrote:

Code: Select all: ...|.6.|97. ..2|..3|5.1 ...|7.5|... ---+---+--- .15|8..|3.. ..9|...|8.. ..7|..9|14. ---+---+--- ...|1.8|... 4.6|5..|7.. .81|.7.|...

which trivially leads to the

Code: Select all: Resolution state after Singles: +-------------+-------------+-------------+ ! 35 35 8 ! 2 6 1 ! 9 7 4 ! ! 9 7 2 ! 4 8 3 ! 5 6 1 ! ! 1 6 4 ! 7 9 5 ! 2 8 3 ! +-------------+-------------+-------------+ ! 6 1 5 ! 8 2 4 ! 3 9 7 ! ! 23 4 9 ! 36 1 7 ! 8 25 256 ! ! 8 23 7 ! 36 5 9 ! 1 4 26 ! +-------------+-------------+-------------+ ! 7 25 3 ! 1 4 8 ! 6 25 9 ! ! 4 9 6 ! 5 3 2 ! 7 1 8 ! ! 25 8 1 ! 9 7 6 ! 4 3 25 ! +-------------+-------------+-------------+

If you want to ignore the most basic rules in order to create abstruse patterns, I can't see what value is created.
As for the x-wing, see the definition on any serious Sudoku website. Nobody needs a solver to find it.

by **kurbads** » Sat Aug 07, 2021 4:58 pm

No, you did not start with what I wrote. That is empty unfilled sheet of the game. The question is pictured in the image of half solved puzzle.

I described a valid problem and a solid solution to it.

You pointed me out a dozen singles as missed while they were filled in on the image which indicates that you have not seen the image.

Since one can not copy and paste the image into an actual app (maybe one can, I just don't know), I posted what I could copy, the source of the game if you wanted to look at it.

But instead of looking at my question and the puzzle, you solved the puzzle from the beginning with an automated tool and posted the steps.

I can myself solve it with automated tool and look at the steps.

I posted a question which you ignored. And still ignore.

Are you fully convinced that the puzzle has to be solved in the sequence your automated tool has decided and therefore cannot lead to the situation I describe?

Here is the image again, maybe you finally want to look at it?

And the question:

If I put 8 in R3C5, it creates a deadly pattern.
Image
But I browsed through the rules and did not notice anything resembling it except Sashimi X-Wing. It leads to different exclusions though.

Is there a rule that is responsible for it, is it sequence of pairs or hidden naked pairs. I wondered if you knew.

by **kurbads** » Sat Aug 07, 2021 5:28 pm

Ok, one more time. I filled only relevant cells.

This is the situation

And this is the deadly pattern

How could it be seen and recognised the best?

What is the rule there? Is there one?

by **kurbads** » Sat Aug 07, 2021 5:37 pm

denis_berthier wrote:
kurbads wrote:which trivially leads to the
CODE: SELECT ALL
Resolution state after Singles:
+-------------+-------------+-------------+
! 35 35 8 ! 2 6 1 ! 9 7 4 !
! 9 7 2 ! 4 8 3 ! 5 6 1 !
! 1 6 4 ! 7 9 5 ! 2 8 3 !
+-------------+-------------+-------------+
! 6 1 5 ! 8 2 4 ! 3 9 7 !
! 23 4 9 ! 36 1 7 ! 8 25 256 !
! 8 23 7 ! 36 5 9 ! 1 4 26 !
+-------------+-------------+-------------+
! 7 25 3 ! 1 4 8 ! 6 25 9 !
! 4 9 6 ! 5 3 2 ! 7 1 8 !
! 25 8 1 ! 9 7 6 ! 4 3 25 !
+-------------+-------------+-------------+

If you want to ignore the most basic rules in order to create abstruse patterns, I can't see what value is created.
As for the x-wing, see the definition on any serious Sudoku website. Nobody needs a solver to find it.

I am not asking about the resolution of singles. And I see your x-wing no problem.

The question is about something entirely different. See above.

By the way, if I try and paste your result code into Jason T Linhart's Sudoku app, it crashes.

I am pretty sure that is the same Jason who admins this website.

by **Leren** » Sat Aug 07, 2021 10:24 pm

OK I'll have a go at this one. The puzzle : ....6.97...2..35.1...7.5....158..3....9...8....7..914....1.8...4.65..7...81.7....

This is how far you can get with singles :

Code: Select all: *-------------------------------* | 35 35 8 | 2 6 1 | 9 7 4 | | 9 7 2 | 4 8 3 | 5 6 1 | | 1 6 4 | 7 9 5 | 2 8 3 | |---------+--------+------------| | 6 1 5 | 8 2 4 | 3 9 7 | | 23 4 9 | 36 1 7 | 8 25 *2-56 | | 8 23 7 | 36 5 9 | 1 4 26 | |---------+--------+------------| | 7 25 3 | 1 4 8 | 6 25 9 | | 4 9 6 | 5 3 2 | 7 1 8 | | 25 8 1 | 9 7 6 | 4 3 25 | *-------------------------------*

Your 5 cell deadly pattern is moot because, although it's sometimes instructive to ignore an easy move to get to a contrived situation to illustrate a move, I don't think most people would agree that ignoring naked or hidden singles is reasonable.

In your case, in your PM diagram you have ignored the naked single 9 in r8c2, which eventually leads to my PM diagram.

Notice that I've set r5c9 to 2. This is to avoid a Deadly Pattern known as a BUG, or Bi-value Universal Grave. You can read about the BUG move, for example, here.

Leren

by **kurbads** » Sun Aug 08, 2021 5:11 am

Yes, I see that in my original example there is a naked single in C2R8.

But understand my disappointment that I bring something interesting I spotted and instead of looking at it, users point out unfilled singles.

Does it really have to be the only logical next step in the game in order to be for it to be possible to discuss?

It is like, "Oh, forget about what you found, come and look at the large number of little splinters you have!"

by **kurbads** » Sun Aug 08, 2021 6:01 am

Leren wrote:OK I'll have a go at this one. The puzzle : ....6.97...2..35.1...7.5....158..3....9...8....7..914....1.8...4.65..7...81.7....

But that is my start puzzle.

I tried it again and I did not encounter the cute layout I had before.

And I actually made a video of solving it.

https://youtu.be/HAchHWcpVww

by **marek stefanik** » Sun Aug 08, 2021 7:54 am

Hi kurbads,

I see no deadly pattern in either of those images.
In the first one there would be one, if there were a 49 pair in r79c7, but since that's not the case, the pattern can be resolved by other means.
If you fill in these singles: 9r8c2, 6r3c2, 2r3c7, 4r9c7; you resolve the pattern from the other end, which is something that wouldn't be possible with a deadly pattern.

The same is true for the other one. It can be resolved by a 1 or 4 you could get in boxes 4679.
In fact, if you have a look at b9, there is a 36 pair in r8c79, then 1r7c7, 8r7c5, 1r3c5, 2r3c4, 6r3c1, 2r1c1 and you get a 18 pair in r5c12 which resolves the pattern.
There is a possibility for a 15UR, but since that would immeadiately break c5, it doesn't provide any new information and vanishes once you resolve c5.

Whenever you are trying to construct a deadly pattern where the cells in a box aren't in a single line, you have to account for information coming from both its tier and its stack, otherwise you will find false positives. There are many threads concerning uniqueness you might want to check out, for example this one.

Marek

by **kurbads** » Sun Aug 08, 2021 11:35 am

If I put 8 in R2C5, all is fine, if i put 8 in R3C5, it leaves 4 linked cells with naked pairs in them. That means R2C5 is 8.
What is it if not a deadly pattern?

Even thought they are not in rectangular, they are in trapeze.
But I agree that filling out these singles: 9r8c2, 6r3c2, 2r3c7, 4r9c7 does resolve the trapeze from the other end.

So what everybody is trying to say here is that if there are unfilled singles, the pattern is not deadly especially if the resolving of the singles leads to dissolution of the pattern.

Ok, I get you. I just felt I was on to something.

by **jco** » Sun Aug 08, 2021 3:45 pm

Hello kurbads,

kurbads wrote:What is it if not a deadly pattern?

The following link may help you to understand what is a deadly pattern and the many possible ones.

Regards,

by **kurbads** » Sun Aug 08, 2021 4:34 pm

jco wrote:Hello kurbads,
kurbads wrote:What is it if not a deadly pattern?

The following link may help you to understand what is a deadly pattern and the many possible ones.

Regards,

I do not need to look at it. Deadly pattern is when there are possible two solutions to the game.

For example when there is a rectangular with 4 naked pairs.

I have however noticed that there sometimes are situations that 4 naked pairs in a rectangular do not automatically mean a deadly pattern e.g. when there is a chain of pairs and the 4 supposedly dead ones are linked to other cells making them undead.

It is quite murky for me. The sudopedia.org is pretty counter-intuitive site.

Also the tons of examples in replies do not make it more tangible.

----

Edit:

It is not the point. Any notion of deadly pattern even if not present should indicate that the solution is somewhere else.

That is what I point out there.

Marek says, he does not see deadly pattern and yes he is right, it is not there. Because I use the possibility of the deadly pattern as means to find out the true solution.

All I am saying is that an option of deadly pattern "if you trust" the creator of the puzzle and I trust Jason, means that the only alternative solution is the solution not its actual presence.

That is why Marek does not see deadly pattern. It is not there. The puzzle is correctly designed.

But its appearance indicates solution.

It seems that there is not a single user on this forum who remotely understands what I am saying.

Edit2:

Why am I always alone and always have a different opinion about everything?

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