| View previous topic :: View next topic |
| Author |
Message |
daj95376
Joined: 23 Aug 2008
Posts: 3854
|
 Posted: Tue May 31, 2011 8:37 pm Post subject: Puzzle 11/05/31: ~ XY |
 |
|
| Code: | +-----------------------+
| 6 8 . | 5 3 . | . . . |
| 5 . . | . . 2 | . . . |
| . . 3 | 8 7 . | 1 . . |
|-------+-------+-------|
| 7 . 4 | . . 8 | 6 9 . |
| 1 . 6 | . 5 9 | . . . |
| . 9 . | 7 6 3 | . . . |
|-------+-------+-------|
| . . 5 | 3 . . | . . 9 |
| . . . | 2 . . | . 8 . |
| . . . | . . . | 5 . 7 |
+-----------------------+
|
Play this puzzle online at the Daily Sudoku site |
|
| Back to top |
|
 |
peterj
Joined: 26 Mar 2010
Posts: 974
Location: London, UK
|
| Posted: Wed Jun 01, 2011 9:24 am Post subject: |
|
|
<ott>
For fun ... notice there is an almost xy-wing(79-1) pivot at r8c3 and this eliminates (1)r2c5 which makes a w-wing(16) in band 3 whole.. conveniently a bivalue (1=6) makes the xywing and the same eliminations as the wwing..
| Code: | | (6=1)r8c9 - (1)r8c3=xywing(79-1)r8c3,r2c3,r8c3 - (1)r2c5=wwing(16)r7c2,r8c9 ; r8c2<>6, r7c8<>6 |
This would be considered inflammatory on "another board"! Hopefully here it will pass off as intersting/amusing and of course OTT for this puzzle!
</ott> |
|
| Back to top |
|
|
tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
|
| Posted: Wed Jun 01, 2011 2:10 pm Post subject: |
|
|
Peter, very  find!
Here is an interesting twist using an identical anp() but reversing the order to solve the puzzle.
anp(12=9)r9c23-als(9=2)r821c3-(2-4)r3c2-(4=6)r3c6-(6=5)r3c8-(5=1)r6c8; r9c8<>1
anp(9=12)r9c32-(1=6)r7c2-r7c8=r3c8-r3c6=(6-1)r9c6; r9c6<>1
Ted |
|
| Back to top |
|
|
ronk
Joined: 07 May 2006
Posts: 398
|
| Posted: Wed Jun 01, 2011 2:29 pm Post subject: |
|
|
| peterj wrote: | For fun ... notice there is an almost xy-wing(79-1) pivot at r8c3 and this eliminates (1)r2c5 which makes a w-wing(16) in band 3 whole.. conveniently a bivalue (1=6) makes the xywing and the same eliminations as the wwing..
| Code: | | (6=1)r8c9 - (1)r8c3=xywing(79-1)r8c3,r2c3,r8c3 - (1)r2c5=wwing(16)r7c2,r8c9 ; r8c2<>6, r7c8<>6 |
|
Haven't figured out how one goes about finding such a thing, but it definitely is interesting. It can be viewed as a chain which doubly-links [an AALS.]
(6=1)r8c9 - (1=79)als:r8c35 - (79=14)aals:r2c35 - (4=1)r7c5 - (1=6)r7c2 ==> r7c8, r8c2<>6
When viewed as a w-wing, there is a derived strong inference (1) r8c35 = (1)r7c5 linking the two bivalues.
[edit: Not sure how one would read the aals chain from right-to-left though.]
Last edited by ronk on Wed Jun 01, 2011 5:08 pm; edited 1 time in total |
|
| Back to top |
|
|
daj95376
Joined: 23 Aug 2008
Posts: 3854
|
| Posted: Wed Jun 01, 2011 4:33 pm Post subject: |
|
|
| Code: | after basics
+--------------------------------------------------------------+
| 6 8 127 | 5 3 14 | 9 27 24 |
| 5 147 17 | 69 149 2 | 78 3 468 |
| 9 24 3 | 8 7 46 | 1 56 2456 |
|--------------------+--------------------+--------------------|
| 7 5 4 | 1 2 8 | 6 9 3 |
| 1 3 6 | 4 5 9 | 78 27 28 |
| 2 9 8 | 7 6 3 | 4 15 15 |
|--------------------+--------------------+--------------------|
| 8 16 5 | 3 14 7 | 2 146 9 |
| 4 167 179 | 2 19 5 | 3 8 16 |
| 3 12 129 | 69 8 146 | 5 14 7 |
+--------------------------------------------------------------+
# 42 eliminations remain
|
My perspective on peterj's solution:
If r8c3=1, then (1=6)r7c2,r8c9 ... and the eliminations follow.
Else r8c3<>1, then two steps: XY-Wing, W-Wing ... and the eliminations follow.
My solver encountered similar logic: just less interesting
If r2c9=4, then r2c9<>6.
Else r2c9<>4 and this chain exists:
(6)r8c9 = (6-7)r8c2 = (7-4)r2c2 = r2c5 - (4=1)r7c5 - (1=6)r7c2 - r8c2 = (6)r8c9 => r2c9<>6 |
|
| Back to top |
|
|
peterj
Joined: 26 Mar 2010
Posts: 974
Location: London, UK
|
| Posted: Wed Jun 01, 2011 5:35 pm Post subject: |
|
|
| ronk wrote: | | Haven't figured out how one goes about finding such a thing, but it definitely is interesting. |
fwiw I have spent the last year on this forum learning patterns, I now find I see almost-patterns relatively naturally (which some might think worrying!). In this case I saw the aw-wing and noticed the 1 was an elimination of the axy-wing - it just read better the other way round!
I know they are nets really but I dont find them that way.
farpointer/kobold on the au forum used them a lot - especially fish - find those harder.
I haven't figured how people find really long AIC with multiple digits and hidden sets - other than just legthy "fishing" I guess. |
|
| Back to top |
|
|
Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
|
| Posted: Thu Jun 02, 2011 4:17 am Post subject: |
|
|
Two M-Wings
12; r9c6<>1
16, flightless with transport; r6c8, r8c9<>1 |
|
| Back to top |
|
|
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
