dailysudoku.com

[nataraj]

Today's puzzle offers ample oppurtunities to use different methods.

It takes a little while to arrive here:

+--------------------------+--------------------------+--------------------------+ 


| 37      2       478      | 1       389     6        | 3579    489     3589     | 


| 9       6       78       | 38      4       5        | 37      1       2        | 


| 1       348     5        | 7       2389    29       | 6       489     389      | 


+--------------------------+--------------------------+--------------------------+ 


| 5       89      2        | 6       89      1        | 4       3       7        | 


| 4       7       89       | 38      23589#  29       | 59      6       1        | 


| 6       1       3        | 59#     7       4        | 2       89      589      | 


+--------------------------+--------------------------+--------------------------+ 


| 23      345     6        | 24      59      8        | 1       7       39       | 


| 8       35      1        | 59      6       7        | 3-9     2       4        | 


| 27      49      479      | 24      1       3        | 8       5       6        | 


+--------------------------+--------------------------+--------------------------+ 

For those who like coloring, some kite options:
(3) col 1, row 8
(9) col 4, row 7

For the wing lovers:
xy-wing boxes 1 and 2
xyz-wing col 5

And (not sure if this is really) a w-wing: two pincers 59 (r5c7 and r8c4), connected by a strong link on 5 in box 5 (#), removing 9 from r8c7.

[andras]

I thought this was going to be a stinker, but in the end the simple xy on 3,7,8 (pivot at R2C3) broke it, though it took me a little while to realise it and I thought there must be something else in there!

But there wasn't!

John

[tlanglet]

Many variations to solve this one. I used coloring on <5> to delete that candidate at r6c9 which solved the puzzle.

Ted

[Marty R.]

I used a 78-73-83 XY-Wing, Remote Pairs on 89 and finished it off with a W-Wing on 59. However, I think I had another 59 cell that was used that doesn't show in nataraj's grid. And I do believe that nataraj's W-Wing is indeed a valid one.

[stevieboy]

OK, so I saw the same 37-78-38 XY-Wing that everybody else saw in rows 1 and 2...however, the "stevieboy" method eliminated the '7' in R1C3...what the heck did I do wrong??

[Asellus]

Hi stevieboy,

Let's make sure you are clear on the XY Wing fundamentals. It is a good idea to identify which cell is the pivot. It is the one that can "see" the other two (the "pincers") which must not be able to "see" each other.

Here, the {37} in r1c1 can only see the {78} in r2c3 (they both share box 1). And, the {38} in r2c4 can also only see the {78} in r2c3 (they share row 2). Since the {78} can see the other two cells, it is the pivot. The {37} and {38} cannot see each other, so we have an XY Wing and they are the pincers.

The pincer digit that makes the eliminations is the one which is NOT in the pivot. So, here it is those <3>s in r1c1 and r2c4. Any <3> that can see both of these is eliminated. Here, there is only one such <3>, in r1c5.

The reasoning: If the pivot is <7>, pincer r1c1 must be <3>. If the pivot is <8>, pincer r2c4 must be <3>. Since those are the only two possibilities, one or both of the pincers must be <3> and any cell that sees both of them cannot be.

[storm_norm]

trying to be a good sport and using the draw/play, I got to this point. don't expect all basics to be filtered out.

[stevieboy]

Asellus, a brilliant explanation! Thank you so much...I will cut and paste, and file away.

BTW, I used to live in Marin County, just down the road from you!

storm_norm, yes, that naked pair eliminates the all of the other <8> down col. 5...leaving the <2> naked pair, as well.

YES, after all that, the whole shabang got solved right away!

You guys are really helping me out!!! The "pair-links" (or, whatever they're called) connecting between boxes is something that I'll be investigating as we go along - questions will be forthcoming as those days go by.

THANKS ALL!

[stevieboy]

hmmm...my quote to storm_norm didn't come out right....I really did have naked pairs mentioned in there!

[storm_norm]

nataraj wrote:

[montalbano1944]

After the basics, an XY wing (378) with pivot at R2C3 removes the 3 from R1C5, and that does it.

[cgordon]

A strange one – I never felt I’d gone far enough with the basics. I found 4 of my favourite ERs but still needed the xy wing - and it would seem that's all I needed.

Could I ask why many of the posted grids I see on this Forum (incl the ones from Nataraj & Storm Norm above) have the numbers squished and unreadable on the left-hand side. (it's like 6 columns compressed into 3). Is that my fault?? I'm very computer literate but maybe my screen is too small. Maybe it's my mouse?

[ravel]

Never had this problem, neither with linux/windows nor with firefox/internet explorer. What OS, browser and graphical resolution do you have ?

[nataraj]

[crunched]

Today's puzzle offered me NO opportunities to resolve it. I have finally quit, and decided to throw the towel in. I will now look (backward) to see how you wizards did this.

[crunched]

Weird. I found the xy-wing that everybody said was the key. I still could not go anywhere after that. Yes I found the naked 89s in column 5 too. But that resulted in a combination of 2-3-5 in column five, and I could not go anywhere after that.
I will run through this and see if I have made a mistake. Mistakes can kill a solution.
In the meantime, those who know what to do after the 3-7-8 xy-wing, removing the 3 in r1, c5, please help me.

[cgordon]

[nataraj]

[nataraj]

[nataraj]

I've changed the formatting in my initial post, from BBCode "code" to HTML "pre". It should now display un-squished even in small windows.

But I like the appearance with "code" much more, plus it is much much easier to just hit the code button than to remember and type in proper HTML tags.

The blank lines are just horrible.

Therefore I don't think I'll xx to the new format, sorry.