dailysudoku.com

moshero3 · Joined: 11 Feb 2012 Posts: 12

+---------------+-------------+------------+
| 345 2 459 | 6 1 49 | 34 8 7 |
| 7 3469 4689 | 48 24 5 | 234 1 269 |
| 468 1 4689 | 3 7 2489 | 5 49 269 |
+---------------+-------------+------------+
| 9 46 1 | 2 5 46 | 8 7 3 |
| 468 467 2 | 478 3 468 | 9 5 1 |
| 358 37 58 | 78 9 1 | 6 2 4 |
+---------------+-------------+------------+
| 2 49 7 | 5 6 3 | 1 49 8 |
| 1 8 3 | 9 24 24 | 7 6 5 |
| 46 5 469 | 1 8 7 | 24 3 29 |
+---------------+-------------+------------+

does anyone has an idea ?

Thanks!

daj95376 · Joined: 23 Aug 2008 Posts: 3854

You missed a basic move in column 1, and then you'll still need a couple of advanced moves.

moshero3 · Joined: 11 Feb 2012 Posts: 12

Marty R. · Posted: Sat Feb 11, 2012 4:36 pm Post subject:

This is the grid with c1 taken further.

George Woods · Joined: 28 Mar 2006 Posts: 304 Location: Dorset UK

If r5c4 is 7 then a deadly rectangle in 46 is set up immediately since r6c4 is 8 and these two leave the 46s in block 4 and 5 clean so r6c4 must be 7. This is a single stepper but as I say I don't like it

moshero3 · Joined: 11 Feb 2012 Posts: 12

hughwill · Joined: 05 Apr 2010 Posts: 424 Location: Birmingham UK

I'm also having major trouble on this one. After the X wing (and a possibly useless XYZ wing removing the 4 from r5c1)
I'm guessing we're into colouring territory and some very long chains. Is this the case or are there some of Marty's
'traditional VH' methods that I'm missing?

Marty R. · Posted: Sat Feb 11, 2012 4:55 pm Post subject:

moshero3 · Joined: 11 Feb 2012 Posts: 12

hughwill · Joined: 05 Apr 2010 Posts: 424 Location: Birmingham UK

moshero3 · Joined: 11 Feb 2012 Posts: 12

thanks all!

really learned a lot !

Marty R. · Posted: Sat Feb 11, 2012 5:20 pm Post subject:

Clement · Posted: Sat Feb 11, 2012 9:13 pm Post subject:

After the basics the skyscraper on 9 r7c28 setting r3c3<>9 and r2c9<>9 results in the following Grid:-

daj95376 · Joined: 23 Aug 2008 Posts: 3854

Using my post of the initial grid:

Ema Nymton · Joined: 17 Apr 2009 Posts: 89

.

Bring your "A" game.

One is sorely challenged to find the subtle interlocking play of this puzzle. Well done.

I was totally stopped until I turned here for help. Thank you all.

Ema Nymton
~@:o?
.

eddieg · Joined: 12 Jan 2006 Posts: 47 Location: San Diego, CA USA

Thanks for the help. Needed the hints. I have never had to substitute values into a square and "force" a UR to materialize like this. Nice technique that I will hopefully get to use again soon.

RobertRattley · Joined: 24 Jun 2007 Posts: 118 Location: Australia

Without exception since the beginning (I've solved them all) every "very hard" can be solved with "hard" techniques (pairs, triples, quadruples and other more basic things) plus

x wing or (very rarely nowadays) swordfish

xy wing

xyz wing

Good luck to all skyscraper builders and this-that-and-the-other rectangle finders etcetera, but in some kind of obsessive purism I refuse to use anything but the above.

So for this puzzle too, though I found it particularly challenging: a pair (35 in column 1), an x wing (8), an xyz wing (467 pinching row 5 column 1 on (4))

and finally a basic: column 2's (4) must be in row 4 or 5 and can't be in row 7.

Again, not to denigrate the other techniques, I encourage fellow solvers to be confident that the wings are always enough. I've been waiting for the creator to introduce "extremely hard" where that confidence would finally fail, but the years have gone by ...

As a mathematician I wonder (vaguely) if some theorem might exist that if a puzzle can be solved with a skyscraper or a (whatever) rectangle or one of the other techniques discussed in this forum, then it can also be solved with wings.

I continue to be thoroughly impressed virtually daily at the ingenuity in the creation of these puzzles. On top of all the other wonders, there is the reliable cross-word-puzzle style symmetry!