| View previous topic :: View next topic |
| Author |
Message |
daj95376
Joined: 23 Aug 2008
Posts: 3854
|
 Posted: Thu Jan 29, 2009 7:20 pm Post subject: Set NNP_2 Puzzle 4 -- Advanced |
 |
|
| Code: | +-----------------------+
| . . . | 5 . 1 | . . . |
| . 7 . | 2 6 . | . . 5 |
| . . 1 | . . 9 | . . 6 |
|-------+-------+-------|
| 9 8 . | . 3 . | . 5 . |
| . 2 . | 1 . . | . 8 7 |
| 1 . 5 | . . 8 | . 3 2 |
|-------+-------+-------|
| . . . | . . . | . . . |
| . . . | 6 1 5 | . 2 . |
| . 1 6 | . 2 3 | . . 8 |
+-----------------------+
|
Play this puzzle online at the Daily Sudoku site
===== ===== ===== ===== ===== ===== ===== ===== ===== Ratings
Can be solved using steps from ...
Basics: Naked/Hidden Single, Naked Pair/Triple, Locked Candidate 1/2
Basics+: Naked Quad, Hidden Pair/Triple/Quad
VH: BUG+1, UR Type 1, X-Wing, XY-Wing, XYZ-Wing
VH+: 2-String Kite, Empty Rectangle, Remote Pair, Skyscraper, Colors, UR Type 2
Advanced: finned/Sashimi X-Wing, Multiple Colors, Swordfish, M-Wing, W-Wing, XY-Chain
Extreme: Jellyfish, (but mostly) Chain |
|
| Back to top |
|
 |
tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
|
| Posted: Fri Jan 30, 2009 5:27 am Post subject: |
|
|
Yet another fun VH type puzzle. Minimal basics and several choices for later techniques. My four step solution was: | Quote: |
A kite <3> with pivots in box <3> (or a choice of ERs),
A Type 2 UR on <78> with no deletions but a strong link <7> in row <1> provided a deletion,
xy-wing <238> with pivot<28> in r1c3 deleted two occurrences and a transport removed an additional <3>,
and finally a w-wing <34> with transport completed the fun |
Ted  |
|
| Back to top |
|
|
storm_norm
Joined: 18 Oct 2007
Posts: 1741
|
| Posted: Fri Jan 30, 2009 8:04 am Post subject: |
|
|
I call these the "Danny specials"
in the image below notice the UR {7,8}. we know from the rules of unique rectangles that you cannot be left with a 7 and a 8 in r1c7 and r3c7...
then notice the other 7 in column 7
and the other 8 in column 7
as in the image
so either the 7 in r8c7 is true or the 8 in r2c7 is true...A.K.A. Strong Inference.
because if both were false then the Deadly Pattern is forced to exist.
if the 7 in r8c7 is true, then the 7 in r8c1 is not true... or if the 7 in r8c7 is not true...
r2c7 = 8
r2c1 <> 8
r8c1 = 8
either way, the 7 in r8c1 is not true.
and solves the puzzle.
or you can view it by this chain.
UR78[(7)r8c7 = (8)r2c7] - (8)r2c1 = (8)r8c1; r8c1 <> 7 |
|
| Back to top |
|
|
tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
|
| Posted: Fri Jan 30, 2009 1:22 pm Post subject: |
|
|
Great find Norm. IMPRESSIVE 
Ted |
|
| Back to top |
|
|
storm_norm
Joined: 18 Oct 2007
Posts: 1741
|
| Posted: Fri Jan 30, 2009 7:17 pm Post subject: |
|
|
thank you, Ted.
this particular move was devastating. I have noticed patterns like this in the other puzzles. Every once in a while one proves critically beneficial. |
|
| Back to top |
|
|
Kdelle
Joined: 20 Mar 2008
Posts: 59
Location: Hudson, NH
|
| Posted: Fri Jan 30, 2009 8:21 pm Post subject: |
|
|
In Norm's diagram above, in order to avoid the deadly pattern 39 in rows 7 and 8, either r7c2 must be 5 or r8c9 must be 4, either of which forces r8c3 = 8 which also solves the puzzle. I think that's correct logic anyway....
Kathy |
|
| Back to top |
|
|
storm_norm
Joined: 18 Oct 2007
Posts: 1741
|
| Posted: Fri Jan 30, 2009 8:50 pm Post subject: |
|
|
| Quote: | | in order to avoid the deadly pattern 39 in rows 7 and 8, either r7c2 must be 5 or r8c9 must be 4, either of which forces r8c3 = 8 |
Kathy, very nice.
I am curious to know how you formed the inferences to show this.
the two chains I see are as follows:
one starts with the 5 and one starts with the 4
UR39[(4)r8c9 = (5)r7c2] - (5=2)r7c1 - (2)r3c1 = (2-8)r1c3 = (8)r8c3; r8c3 <> 4
uR39[(5)r7c2 = (4)r8c9] - (4)r8c13 = (4-7)r9c1 = (7-8)r8c1 = (8-3)r2c1 = (3-4)r1c2 = (4)r3c2; r3c2 <> 5
as you can see, the one that starts with 5 eliminates the 5 in r3c2
and the one that starts with the 4 does what you pointed out. |
|
| Back to top |
|
|
daj95376
Joined: 23 Aug 2008
Posts: 3854
|
| Posted: Fri Jan 30, 2009 10:34 pm Post subject: |
|
|
Norm, once you have the UR strong link, you can apply forcing chain logic -- my preference.
| Code: | UR39[(4)r8c9 = (5)r7c2]
(4)r4c8 - (4=8)r8c3
(5)r7c2 - (5=2)r7c1 - (2=3)r7c3 - (3=4)r5c3 - (4=8)r8c3
|
However, if you really want an AIC ...
| Code: | (8=4)r8c3 - UR39[(4)r8c9 = (5)r7c2] - (5=2)r7c1 - (2=3)r7c3 - (3=4)r5c3 - (4=8)r8c3
___________________________________________________________________________________
|
|
|
| Back to top |
|
|
Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
|
| Posted: Fri Jan 30, 2009 11:33 pm Post subject: |
|
|
How about an alternate solution? The 78 UR contains two Hidden URs. Because of the strong link on 7 in row 1, the 8 is removed from r3c7. Because of the strong link on 8 in row 3, the 7 is removed from r1c7.
The 39 UR is a standard Type 6 (X-Wing on 9), so the 9s must be present in both the bivalue cells. The puzzle is now reduced to a BUG+1, with r8c1 = 4 in order to squash the BUG. |
|
| Back to top |
|
|
Kdelle
Joined: 20 Mar 2008
Posts: 59
Location: Hudson, NH
|
| Posted: Sat Jan 31, 2009 8:42 am Post subject: |
|
|
Norm,
My thinking was that a 5 in r7c2 forced a 2 in r7c1 which forced a 3 in r7c3 and then a 4 i r5c3....eliminating a 4 in r8c3. I think that's probably what Danny was saying in his post....but I'm not sure I understand his language yet!!!!!!!!! I AM trying!
Kathy |
|
| Back to top |
|
|
storm_norm
Joined: 18 Oct 2007
Posts: 1741
|
| Posted: Sat Jan 31, 2009 6:33 pm Post subject: |
|
|
| Kdelle wrote: | Norm,
My thinking was that a 5 in r7c2 forced a 2 in r7c1 which forced a 3 in r7c3 and then a 4 i r5c3....eliminating a 4 in r8c3. I think that's probably what Danny was saying in his post....but I'm not sure I understand his language yet!!!!!!!!! I AM trying!
Kathy |
ok, very good. as you can see there are many chains to go about eliminating the 4 in r8c3. my first chain does it, danny's chain does it and your chain does it...
by the way, your chain would look like this
UR78[(4)r8c9 = (5)r7c2] - (5=2)r7c1 - (2=3)r7c3 - (3=4)r5c3; r8c3 <> 4 |
|
| Back to top |
|
|
Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
|
| Posted: Wed Feb 04, 2009 10:54 pm Post subject: |
|
|
I just got around to doing this, even though I've already commented.
An XY-Wing on 283 took out a couple of 3s, then a pincer transport made more eliminations. A W-Wing on 34 with pincer transport finished it off. |
|
| Back to top |
|
|
Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
|
| Posted: Wed Feb 04, 2009 11:42 pm Post subject: |
|
|
Norm,
While the 78UR route to your elimination is fine, it isn't necessary:
(7)r8c1 - (7=3)r8c7 - (3=8)r2c7 - (8)r2c1=(8-7)r8c1; r8c1<>7
It is just a 2-cell XY-Chain extended with a conjugate link. Thus, a simple one-step solution without uniqueness assumptions. |
|
| Back to top |
|
|
daj95376
Joined: 23 Aug 2008
Posts: 3854
|
| Posted: Thu Feb 05, 2009 1:08 am Post subject: |
|
|
This puzzle offers a host of solution paths ... and I don't mean all of the long XY-Chains.
| Code: | after basics and before ER eliminations on <3> -- Norm's PM
+-----------------------------------------------------+
| 6 @34 28 | 5 78 1 | 278 9 34 |
| 38 7 9 | 2 6 4 | 38 1 5 |
| 25 %45 1 | 3 78 9 | 278 *47 6 |
|-----------------+-----------------+-----------------|
| 9 8 7 | 4 3 2 | 6 5 1 |
| @34 2 34 | 1 5 6 | 9 8 7 |
| 1 6 5 | 7 9 8 | 4 3 2 |
|-----------------+-----------------+-----------------|
| 25 359 23 | 8 4 7 | 1 6 39 |
| 478 39 48 | 6 1 5 | 37 2 349 |
| %47 1 6 | 9 2 3 | 5 *47 8 |
+-----------------------------------------------------+
# 30 eliminations remain
|
Useless Skyscraper in [r39] for <4>. Non-aligned end cells (%) each see a bivalue <34> cell (@). Mayhem follows.
(Personally, I prefer to think of this as a W-Wing on steroids.)
If you perform the ER eliminations on <3>, then there is another W-Wing on steroids present. Whose up for M-Wings on steroids? |
|
| Back to top |
|
|
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
