Can this be done with no trail and error?

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Can this be done with no trail and error?

Postby villagegreen » Sat Mar 11, 2006 9:05 am



_ 9 1 7 _ 6 _ 3 2

6 _ 2 4 1 3 7 9 _

3 _ 7 9 2 _ _ 1 6

_ 3 4 2 7 _ 1 6 9

2 6 9 1 3 4 _ 7 _

1 7 _ 6 _ 9 3 2 4

9 _ _ 3 _ 7 2 _ 1

_ 2 3 8 9 1 6 _ 7

7 1 _ 5 _ 2 9 _ 3

[/img]
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Postby tarek » Sat Mar 11, 2006 9:44 am

hi villagegreen,

advanced techniques for this one,

Depends on your def of T&E

easiest probably is colouring of 8s........

a finned x-wing formation in 8s (column 1 & 5) would also solve the puzzle.........

Tarek
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Postby Kent » Sat Mar 11, 2006 9:57 am

Tarek
easiest probably is colouring of 8s........

a finned x-wing formation in 8s (column 1 & 5) would also solve the puzzle.........



Is it possible to start colouring from r1c1?? If can then how to continue as there's 3 candidates of '8' in row 1.Will the r1c5 or the r1c7 be the conjugate of r1c1??

Where would the fin be??
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Postby tarek » Sat Mar 11, 2006 12:03 pm

I dislike this type of colouring elimination, however when present, it provides massive eliminations......

Code: Select all
*-----------------------------------------------*
|A458  9    1   | 7   A58   6   | 458  3    2   |
| 6    58   2   | 4    1    3   | 7    9    58  |
| 3    458  7   | 9    2   a58  | 458  1    6   |
|---------------+---------------+---------------|
|a58   3    4   | 2    7   A58  | 1    6    9   |
| 2    6    9   | 1    3    4   | 58   7    58  |
| 1    7   A58  | 6   a58   9   | 3    2    4   |
|---------------+---------------+---------------|
| 9    458  568 | 3    46   7   | 2    458  1   |
| 45   2    3   | 8    9    1   | 6    45   7   |
| 7    1    68  | 5    46   2   | 9    48   3   |
*-----------------------------------------------*
Eliminating 8 From r1c1,r1c5,r4c6,r6c3 (Simpe Couloring)


Kent, if you start from r1c1, the chain of conjugates is possible if you look at column 1 rather than Row 1 or Box 1, we finish with 2 candidates with same colour (A) in row 1, a contradiction....
So you can safely eliminate the candidates color coded (A)

Code: Select all
*-----------------------------------------------*
|*458  9    1   | 7   *58   6   | 458  3    2   |
| 6    58   2   | 4    1    3   | 7    9    58  |
| 3    458  7   | 9    2    58  | 458  1    6   |
|---------------+---------------+---------------|
|#58   3    4   | 2    7    58  | 1    6    9   |
| 2    6    9   | 1    3    4   | 58   7    58  |
|*1    7   -58  | 6   *58   9   | 3    2    4   |
|---------------+---------------+---------------|
| 9    458  568 | 3    46   7   | 2    458  1   |
| 45   2    3   | 8    9    1   | 6    45   7   |
| 7    1    68  | 5    46   2   | 9    48   3   |
*-----------------------------------------------*
Eliminating 8 From r6c3 (Finned XWing in Columns 15)


Here is variation of your normal finned x-wing (one step higher), the sashimi variation, or if you want an Almost finned x-wing, refer to the filet-o-fish thread for more info.
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Postby Kent » Sat Mar 11, 2006 12:14 pm

The * doesnt form an X wing.The candidate at r6c1 is a 1 while the rest of the cells are 5 and 8.I thought all cells have to have the same candidate to form a x -wing
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Can this be done with no trail and error?

Postby Cec » Sat Mar 11, 2006 3:06 pm

Kent wrote:The * doesnt form an X wing..."

Kent, Looking through this thread I can't see any reference, apart from your own, that the * forms an x-wing. Tarek's above code and explanation refers to a finned x-wing as indicated by this * in c15r16. Therefore, that particular pattern cannot be also recognized as an x-wing because these two patterns are different.

Kent wrote:"..The candidate at r6c1 is a 1 while the rest of the cells are 5 and 8.I thought all cells have to have the same candidate to form a x -wing

As this statement suggests you understand the requirements for an x-wing pattern I can't understand why you raised the first query?
On another matter, to avoid confusion to readers, it is better to use the forum's recommended terminology. For example, the digit 1 you refer to at r6c1 is not a candidate - it is a "clue" or given number for the puzzle.

For what it's worth, I received much help when I joined the forum and there's still much more for me to learn. During my "initiation" it was suggested to make sure I fully understood the "basic" stuff before venturing into the advanced techniques - I'm still embarressed when I think back to my "early" days of suggesting an alternative definition for the x-wing pattern because I didn't like angusj's wording. I appreciated when puzzles were posted by others in the clear manner described Here so I learnt how to do this properly. People want to help you and I hope you accept this in the spirit that it's given.
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Postby Kent » Sat Mar 11, 2006 4:14 pm

Cec


What i am saying is that * doesn't form an X-wing at all.Please don't get me wrong.Because Tarek said * forms an X wing.So I just wanted to clarify that it doesn't form an X-wing as it doesn't fulfil the cirteria for an x-wing.So please don't get me wrong.I'm not trying to change the rules of X-wing.Just to point out to Tarek that it doesn't form an X-wing.Thanks
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Postby tarek » Sat Mar 11, 2006 4:54 pm

Kent wrote:Just to point out to Tarek that it doesn't form an X-wing.Thanks


Hi Kent,

The easiest way to (spot/imagine) a finned x-wing is to take the (fin or fins) out, if the remaining candidates form a valid x-wing then you have discovered your finned x-wing....

In the example above, it is a bit different & a bit harder, I added a paragraph after it hoping not to cause confusion for people starting to understand this technique, I'm just going to repeat it again:
tarek wrote:Here is variation of your normal finned x-wing (one step higher), the sashimi variation, or if you want an Almost finned x-wing, refer to the filet-o-fish thread for more info

I was hoping that you would go & read about it, as indeed it doesn't follow that general principle you've been applying.

I noticed that you've been covering too many different advanced techniques which are new to you in a very short period of time.... That is bound to cause confusion.

My advice would be to master x-wings, sworfishes, jellyfishes first...
Then master the finned x-wing (following the general principle you've been following), then go for the variation (the example above).....

Unfortunately, this means too much homework & some reading prior to moving to the next step.......

if you reduce the tap water strength you'll still fill the sink -over a longer period maybe- but without the splatter.

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Thanks but . . .

Postby villagegreen » Sat Mar 11, 2006 6:28 pm

Thanks a lot guys, but I have no idea what you're talking about. I just solve these puzzles as they come in the paper and this is the first one that I haven't been able to solve. I have no idea whatsoever about x-wings, coloring, sashmi, fins or anything else. I'd just like to know what's the next number and why?
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Postby Kent » Sat Mar 11, 2006 7:04 pm

Thanks Tarek.I think my problem is i tend to be too eager to learn lots of stuff when i cant master those new ones.I think i'll stick to what u say. Can u help me with this prob??

1)I tried forcing chain.Can i deduce like this : r1c4=3->r2c4=5-> r3c6=2->r3c7=5->r2c9=3->r1c9=2 and therefore r1c4=3.So r1c4=3.Can i deduce like this??

2) Can I form a finned X-wing using candidate 4 in cells r4r6,r4r7,r6c6,c6c7??


549l.87l61.
276l.91l84.
183l46.l.97
.61l.3.l.79
.35l..9l1..
792l.1.l...
327l156l984
914l.2.l.56
658l9..l..1
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Postby tso » Sat Mar 11, 2006 8:12 pm

tarek wrote:I dislike this type of colouring elimination,


Why?


Code: Select all
*-----------------------------------------------*
|*458  9    1   | 7   *58   6   | 458  3    2   |
| 6    58   2   | 4    1    3   | 7    9    58  |
| 3    458  7   | 9    2    58  | 458  1    6   |
|---------------+---------------+---------------|
|#58   3    4   | 2    7    58  | 1    6    9   |
| 2    6    9   | 1    3    4   | 58   7    58  |
|*1    7   -58  | 6   *58   9   | 3    2    4   |
|---------------+---------------+---------------|
| 9    458  568 | 3    46   7   | 2    458  1   |
| 45   2    3   | 8    9    1   | 6    45   7   |
| 7    1    68  | 5    46   2   | 9    48   3   |
*-----------------------------------------------*
Eliminating 8 From r6c3 (Finned XWing in Columns 15)


Here is variation of your normal finned x-wing (one step higher), the sashimi variation, or if you want an Almost finned x-wing, refer to the filet-o-fish thread for more info.



I have to side with Kent here. There are simply too many arbitrary and hard to tell apart names for tactics. It's one thing if the logic is difficult, but another if the terminology and symbology is opaque. It's supposed to make it *easier* for us, not make as special club of in-the-know-it-alls. It's even more difficult since you called it a finned x-wing though it isn't -- it's another "one step higher" variation. Confusing.

The pattern you have described here was called Turbofish long ago. It's also a simple coloring exclusion or a short x-chain as well as set of remote locked pairs. Why must we confuse the issue with yet another name? I don't believe this makes it any easier to spot -- and that is the whole point.


R4c1 and r1c5 are a remote locked pair -- this eliminates both 5 and 8 from r1c1.
Coloring 5s and then 8s makes the same exlusions.
The cells marked with '#' and '-' form a Turbofish.
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Re: Thanks but . . .

Postby tso » Sat Mar 11, 2006 8:18 pm

villagegreen wrote:Thanks a lot guys, but I have no idea what you're talking about. I just solve these puzzles as they come in the paper and this is the first one that I haven't been able to solve. I have no idea whatsoever about x-wings, coloring, sashmi, fins or anything else. I'd just like to know what's the next number and why?


There is no "next number". There are many ways to proceed. For most of us solvers, a puzzle like this will require a candidate grid -- a grid which shows the remaining candidates in each unsolved cell. No way of knowing from your post how far progressed since you didn't include one. See this post for details.

Position given:
Code: Select all
 *-----------*
 |.91|7.6|.32|
 |6.2|413|79.|
 |3.7|92.|.16|
 |---+---+---|
 |.34|27.|169|
 |269|134|.7.|
 |17.|6.9|324|
 |---+---+---|
 |9..|3.7|2.1|
 |.23|891|6.7|
 |71.|5.2|9.3|
 *-----------*


Candidate grid
Code: Select all
 *--------------------------------------------------*
 |{458} 9    1    | 7   [58]  6    | 458  3    2    |
 | 6    58   2    | 4    1    3    | 7    9    58   |
 | 3    458  7    | 9    2    58   | 458  1    6    |
 |----------------+----------------+----------------|
 |[58]  3    4    | 2    7    58   | 1    6    9    |
 | 2    6    9    | 1    3    4    | 58   7    58   |
 | 1    7   [58]  | 6   [58]  9    | 3    2    4    |
 |----------------+----------------+----------------|
 | 9    458  568  | 3    46   7    | 2    458  1    |
 | 45   2    3    | 8    9    1    | 6    45   7    |
 | 7    1    68   | 5    46   2    | 9    48   3    |
 *--------------------------------------------------*



Once a puzzle gets to the point where there are a lot of 'bivalue' cells, that is, cells that have only two possibilites, there will usually be many choices that will solve the puzzle. Here's one, probably the easiest to spot:

Look at the four cells in brackets. Any value in any one of them will elminate both 5 and 8 from r1c1. For example:

Code: Select all
r4c1=5 -> r1c1<>5
r4c1=8 -> r6c3=5 -> r6c5=8 -> r1c5=5 -> r1c1<>5
Therefore, r1c1<>5


Similarly
r4c1=8 -> r1c1<>8
r4c1=5 -> r6c3=8 -> r6c5=5 -> r1c5=8 -> r1c1<>8
Therefore, r1c1<>8

Since r1c1 is not 5 or 8, it must be 4.


Since all possiblities lead to the same conclusion, that conclusion MUST be true. Therefore, r1c1=4.


This is called a remote pair.
Last edited by tso on Sat Mar 11, 2006 4:28 pm, edited 2 times in total.
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Postby Kent » Sat Mar 11, 2006 8:20 pm

How about puzzle where most of the cells are not bivalue? What if they are multivalue?? Can this method be used??
Tso do you use sudoku susser??
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Postby tso » Sat Mar 11, 2006 8:42 pm

Kent wrote:How about puzzle where most of the cells are not bivalue? What if they are multivalue?? Can this method be used??
Tso do you use sudoku susser??


There may be some confusion with the distinction between a "pattern" and a "method". A pattern is either there or it isn't. You can use many methods to try to find these patterns. You will not succeed unless the pattern is actually there. I cannot answer your questions directly as they are much to vauge. How about them Red Sox? I dunno, how about them?

Remote Pairs is just one of many patterns. It is made from -- drumroll -- pairs. Please read the link on remote pairs. It has all there is to know on the subject with purty pictures as well.

When solving for fun, I generally use Simple Sudoku as I find it easier to use. Susser has the advantage that you can turn off tactics of your choice and let it solve what you consider the easy part for you. It also exports nicer starting grids.
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Postby Kent » Sat Mar 11, 2006 8:47 pm

Tso i really need help on susser.I posted this but no one answered me.I just wanna know 1 thing.In susser, how do u make pencilmark when u are tyring to solve a puzzle?? I can only insert a candidate but not pencilmarking the possible candidatees.I read the manul but it's not stated.Would really appreaciate it if u could tell me.Anyway, simple sudoku can't pencilmark the candidates too now that i relise it.Thanks
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