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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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 Posted: Mon Apr 06, 2009 3:18 am Post subject: April 6 VH |
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Either a skyscraper <5>, or a UR (16) will do it in one stroke.
The 358 xy-wing is not a single-step solution.
Any silver bullets out there?
Early Earl |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Mon Apr 06, 2009 5:01 am Post subject: |
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| I avoided the UR and used the 583 Wing plus a Kite on 5. |
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George Woods
Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK
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| Posted: Mon Apr 06, 2009 8:35 am Post subject: w wing? |
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| a w wing (35) after 25 moves solved it for me! |
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LloydB
Joined: 09 Jul 2007
Posts: 21
Location: Skagit Co., WA USA
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| Posted: Mon Apr 06, 2009 10:53 am Post subject: |
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| A pair of 358 XY wings did it for me. |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Mon Apr 06, 2009 12:12 pm Post subject: |
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| There are a veritable plethora of one-steppers incl. Type 4 URs on 16 & 34; and an ER or the skyscraper on 5. An easy very hard. |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Mon Apr 06, 2009 12:41 pm Post subject: Re: April 6 VH |
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| Earl wrote: |
The 358 xy-wing is not a single-step solution |
I agree, but a xy-wing <358> with pincer transport is a single-step solution.
xy-wing <358> with pivot <38> at r9c8 and pseudo-cell <58> in r3c78 deletes <5> in r3c4 & r9c7. Then transport <5> in pincer r9c4 => r9c9 => r8c9; delete <5> r2c9.
I do realize that my xy-wing with a pseudo-cell pincer is also a w-wing but I found it looking for a xy-wing. It could also be called w-wing with transported pincers.
Ted |
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chesterdad
Joined: 06 Apr 2009
Posts: 6
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| Posted: Mon Apr 06, 2009 8:44 pm Post subject: What are you talking about??? |
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I don't understand your lexicon. W's X's UR's etc. Can you point me to your dictionary?
I just re-read the instructions and note that the puzzles on this site can be solved by logic alone. I can solve today's puzzle (6 Apr 2009) up to the point shown. The logic for the next step escapes me.
The Hint tells me to put a 3 in the square with the X. Can someone explain what logic provides this answer?
b = blank
b b b b 2 7 6 4 1
b 7 b b X 4 2 9 b
b 4 2 b 9 b b b 7
8 6 1 9 5 2 b 7 b
7 5 3 4 6 8 1 2 9
9 2 4 7 1 3 8 5 6
4 b b b b b 7 1 2
b 8 7 2 4 1 9 6 b
2 1 6 b 7 9 b b b |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Mon Apr 06, 2009 9:40 pm Post subject: Re: What are you talking about??? |
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| chesterdad wrote: | I don't understand your lexicon. W's X's UR's etc. Can you point me to your dictionary?
I just re-read the instructions and note that the puzzles on this site can be solved by logic alone. I can solve today's puzzle (6 Apr 2009) up to the point shown. The logic for the next step escapes me.
The Hint tells me to put a 3 in the square with the X. Can someone explain what logic provides this answer?
b = blank
b b b b 2 7 6 4 1
b 7 b b X 4 2 9 b
b 4 2 b 9 b b b 7
8 6 1 9 5 2 b 7 b
7 5 3 4 6 8 1 2 9
9 2 4 7 1 3 8 5 6
4 b b b b b 7 1 2
b 8 7 2 4 1 9 6 b
2 1 6 b 7 9 b b b |
just for clarification here is the grid that you provided but with all the pencil marks A.K.A PMs
| Code: | .---------------------.---------------------.---------------------.
|A35 39 589 | 358 2 7 | 6 4 1 |
|C1356 7 58 | 13568 38 4 | 2 9 358 |
|D1356 4 2 | 13568 9 56 | 35 38 7 |
:---------------------+---------------------+---------------------:
| 8 6 1 | 9 5 2 | 34 7 34 |
| 7 5 3 | 4 6 8 | 1 2 9 |
| 9 2 4 | 7 1 3 | 8 5 6 |
:---------------------+---------------------+---------------------:
| 4 39 59 | 3568 38 56 | 7 1 2 |
|B35 8 7 | 2 4 1 | 9 6 35 |
| 2 1 6 |E358 7 9 | 345 F38 G3458 |
'---------------------'---------------------'---------------------' |
now that 3 placement you asked about in row 2 column 5 comes about by doing several more basic steps.
notice the naked pair in A and B, removes the 3 and 5 from C and D
and notice the intersection in row 9
8 can't exist at E because only the 8 can exist in box 9 at F and G (pointing pair) so 8 can be eliminated from E.
brings you to this grid.
| Code: | .---------------------.---------------------.---------------------.
|A35 B39 589 |C358 2 7 | 6 4 1 |
|D16 7 58 |E13568 38 4 | 2 9 358 |
| 16 4 2 | 13568 9 56 | 35 38 7 |
:---------------------+---------------------+---------------------:
| 8 6 1 | 9 5 2 | 34 7 34 |
| 7 5 3 | 4 6 8 | 1 2 9 |
| 9 2 4 | 7 1 3 | 8 5 6 |
:---------------------+---------------------+---------------------:
| 4 39 59 | 3568 38 56 | 7 1 2 |
| 35 8 7 | 2 4 1 | 9 6 35 |
| 2 1 6 | 35 7 9 | 345 38 3458 |
'---------------------'---------------------'---------------------' |
now notice the pointing pair in row 1 in A and B, removes 3 from C.
and now comes the hard move to see.
notice how the candidates 1 and 6 only appear in row 2 at D and E
this is a hidden pair.
1 and 6 are the only values that can exist in those cells.
3,5 and 8 can be removed from E
gets too..
| Code: | .---------------------.---------------------.---------------------.
| 35 39 589 |B58 2 7 | 6 4 1 |
| 16 7 58 | 16 A38 4 | 2 9 358 |
| 16 4 2 |D13568 9 56 | 35 38 7 |
:---------------------+---------------------+---------------------:
| 8 6 1 | 9 5 2 | 34 7 34 |
| 7 5 3 | 4 6 8 | 1 2 9 |
| 9 2 4 | 7 1 3 | 8 5 6 |
:---------------------+---------------------+---------------------:
| 4 39 59 | 3568 E38 56 | 7 1 2 |
| 35 8 7 | 2 4 1 | 9 6 35 |
| 2 1 6 |C35 7 9 | 345 38 3458 |
'---------------------'---------------------'---------------------' |
notice A B and C form a xy-wing on {3,5,8} with pivot cell at B
this particular xy-wing says that the pincer candidate is 3
both 3's "see" the 3 at D and E. removing the 3 at D and E leaves the only 3 in box 2 and column 5 at A.
Last edited by storm_norm on Mon Apr 06, 2009 10:02 pm; edited 5 times in total |
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chesterdad
Joined: 06 Apr 2009
Posts: 6
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| Posted: Mon Apr 06, 2009 9:42 pm Post subject: |
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| Thanks Norm! |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Mon Apr 06, 2009 9:55 pm Post subject: |
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| sorry I edited it while you were posting |
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chesterdad
Joined: 06 Apr 2009
Posts: 6
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| Posted: Mon Apr 06, 2009 10:12 pm Post subject: |
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I am with you all the way to the last three lines, Norm.
Can you point me to some background on an xy wing? And the pincer it makes? These are new terms for me...
I can see the triple <3> at row2col9 -- but that didn't seem to play into your explanation.
I think my confusion lies in the xy wing and the terminology.
Thanks! |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Mon Apr 06, 2009 11:57 pm Post subject: |
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| chesterdad wrote: | I am with you all the way to the last three lines, Norm.
Can you point me to some background on an xy wing? And the pincer it makes? These are new terms for me...
I can see the triple <3> at row2col9 -- but that didn't seem to play into your explanation.
I think my confusion lies in the xy wing and the terminology.
Thanks! |
what you will find is that it actually had two names, the name "y-wing" being faded out over time.
the confusion will be worst when trying to decipher the different meanings of words and terms and hints that are used to define a xy-wing.
the light at the end of the tunnel is pretty bright and may leave you blind for a while. once you come out on the other side, your sudoku solving days will never be the same and the learning curve will resemble a mighty fine ski slope.
http://www.playr.co.uk/sudoku/solving.xywing.php
http://www.brainbashers.com/sudokuxywing.asp
one of our very own posters, nataraj, created a thread to help in searching for the wings. its entertaining and educational.
http://www.dailysudoku.com/sudoku/forums/viewtopic.php?t=2338&sid=a492efaaf663f570e5f2b230d1b4eba6 |
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chesterdad
Joined: 06 Apr 2009
Posts: 6
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| Posted: Tue Apr 07, 2009 2:04 pm Post subject: |
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I am most grateful! For both the links and the tutoring!!!
Thanks! |
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