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Johan
Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium
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 Posted: Wed Oct 10, 2007 12:30 pm Post subject: Oct 10 VH |
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Three steps for this one
1. XY-wing with pivot in R9C7
2. Then using the strong link on <1> in R6, which results in three weak links in R5C7, R5C8 and R9C4.
3. XY-wing with pivot in R6C4.
This is the grid after basic steps
| Code: |
+--------------+------------+--------------+
| 5 17 9 | 2 34 34 | 178 18 6 |
| 2 6 8 | 7 1 9 | 3 5 4 |
| 137 137 4 | 8 6 5 | 127 12 9 |
+--------------+------------+--------------+
| 13 9 5 | 4 8 123 | 6 7 123 |
| 4 123 6 | 9 7 123 | 18 138 5 |
| 137 8 237 | 13 5 6 | 4 9 123 |
+--------------+------------+--------------+
| 8 3457 37 | 135 2 134 | 9 6 13 |
| 9 234 1 | 6 34 7 | 5 234 8 |
| 6 2345 23 | 135 9 8 | 12 1234 7 |
+--------------+------------+--------------+
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Captain Pete
Joined: 09 Jun 2007
Posts: 55
Location: Oley, PA
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| Posted: Wed Oct 10, 2007 1:20 pm Post subject: 9/10 VH and links |
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Using your numbers, I reduced this puzzle to the grid below. You identify a strong link in R6, and I see that. But my understanding is that strong links must come in pairs to eliminate numbers, and I only see one strong link. How do you get from the strong link in R6 to the weak links you identify?
| 5 17 9 | 2 34 34 | 178 18 6 |
| 2 6 8 | 7 1 9 | 3 5 4 |
| 13 137 4 | 8 6 5 | 127 12 9 |
+--------------+------------+--------------+
| 13 9 5 | 4 8 123 | 6 7 123 |
| 4 123 6 | 9 7 123 | 18 138 5 |
| 7 8 23 | 13 5 6 | 4 9 123 |
+--------------+------------+--------------+
| 8 45 7 | 135 2 134 | 9 6 13 |
| 9 234 1 | 6 34 7 | 5 234 8 |
| 6 2345 23 | 135 9 8 | 12 1234 7 |
+--------------+------------+--------------+ |
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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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| Posted: Wed Oct 10, 2007 2:22 pm Post subject: Oct 10 VH |
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I used a finned X-wing on the 1's in R67, C49 TWICE to eliminate the 1's in R7C6 and R9C4. Is that legitimate?
Earl |
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sheryl
Joined: 24 Sep 2007
Posts: 64
Location: New York
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| Posted: Wed Oct 10, 2007 3:11 pm Post subject: |
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| can you explain better. i got down to the grid that you have displayed but i just don't understand how you eliminate anything further. X wings and finned xwings are confusing. is there any way you can explain in more detail. thanks. |
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Johan
Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium
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| Posted: Wed Oct 10, 2007 3:22 pm Post subject: |
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| Quote: |
How do you get from the strong link in R6 to the weak links you identify?
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Pete,
This is the grid using the strong link on <1> in R6, being a P & P solver i give the strong link a <+>value for true(=1) and a <->value for not true
A. R6C4=+(=1)
| Code: | +-------+-------+-------+
| . . . | . . . | . . . |
| . . . | . . . | . . . |
| . . . | . . . | . . . |
+-------+-------+-------+
|-1 . . | . . -1| . . +1|
| .+1 . | . . -1|-1 -1. |
| . . . |+1 . . | . . -1|
+-------+-------+-------+
| . . . |-1 . +1| . . -1|
| . . . | . . . | . . . |
| . . . |-1 . . |+1 +1. |
+-------+-------+-------+
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B. R6C9=+(=1)
| Code: |
+-------+-------+-------+
| . . . | . . . | . . . |
| . . . | . . . | . . . |
| . . . | . . . | . . . |
+-------+-------+-------+
| 1 . . | . . +1| . . -1|
| . 1 . | . . +1|-1 -1. |
| . . . |-1 . . | . . +1|
+-------+-------+-------+
| . . . |+1 . -1| . . -1|
| . . . | . . . | . . . |
| . . . |-1 . . |+1 +1. |
+-------+-------+-------+
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This is the composition of the two grids (A + B), only using the double weak links on <1>
| Code: |
+-------+-------+-------+
| . . . | . . . | . . . |
| . . . | . . . | . . . |
| . . . | . . . | . . . |
+-------+-------+-------+
| 1 . . | . . 1 | . . 1 |
| . 1 . | . . 1 |-1- -1-|
| . . . | 1 . . | . . 1 |
+-------+-------+-------+
| . . . | 1 . 1 | . .-1-|
| . . . | . . . | . . . |
| . . . |-1-. . | 1 1 . |
+-------+-------+-------+
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And oops there are four weak links on <1> instead of three. |
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sdq_pete
Joined: 30 Apr 2007
Posts: 119
Location: Rotterdam, NL
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| Posted: Wed Oct 10, 2007 4:42 pm Post subject: |
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Following the basic eliminations I reached the position as given by Johan.
I then found a surprisingly long sequence of 'X' moves, namely:
XYZ 134 R7C6
XY 123 R9C7
CX 3 C34
XY 123 R6C3
XY 123 R6C9
(where my shorthand gives the technique, the digits involved and the pivot, or, in the case of the X-wing, CX for "column X-wing", C34 on columns 3 and 4)
The position after all this was:
| Code: |
+-----------+------------+------------+
| 5 17 9 | 2 34 34 | 178 18 6 |
| 2 6 8 | 7 1 9 | 3 5 4 |
| 13 137 4 | 8 6 5 | 127 12 9 |
+-----------+------------+------------+
| 13 9 5 | 4 8 12 | 6 7 23 |
| 4 123 6 | 9 7 123 | 18 138 5 |
| 7 8 23 | 13 5 6 | 4 9 12 |
+-----------+------------+------------+
| 8 45 7 | 15 2 134 | 9 6 13 |
| 9 234 1 | 6 34 7 | 5 234 8 |
| 6 245 23 | 135 9 8 | 12 124 7 |
+-----------+------------+------------+
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at which point I needed to resort to "non-standard" logic i.e. non-X-moves. Observing the 12 candidate pairs in blocks 3, 6 and 9, I noticed that whatever value R9C7 took, R6C9 must be 1. Intuitively, I suspect this is related to Johan's links. But can anyone identify any further x-moves here?
Peter |
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duffy
Joined: 13 Sep 2007
Posts: 26
Location: Toronto Canada
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| Posted: Wed Oct 10, 2007 8:36 pm Post subject: |
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Earl wrote: | Code: | | I used a finned X-wing on the 1's in R67, C49 TWICE to eliminate the 1's in R7C6 and R9C4. Is that legitimate? |
I think re-wording might help to legitimize: One could say that there is a finned x-wing that will make one of these eliminations, and then without making any changes say there is a different one that will make the other elimination. Thus both are justified.
Sheryl,
Marty responded to me with a good explanation for a finned x-wing in the recent "sept 19" posting. Separately, I would suggest getting a good handle on the x-wing so that it stops being confusing. The xy- and xyz-wings are fascinating and different.
Don D. |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Thu Oct 11, 2007 1:29 am Post subject: |
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I found this one a real challenge - one of the hardest I can recall. After a skyscraper, one xy and two xyz wings, I couldn't get any further than this. No more x-y-z or w wings, no URs, ERs or skyscrapers. Someone lead me out the wilderness please. (No chains though - I'm not into chains).
| Code: |
+-------------+-----------+--------------+
| 5 137 9 | 2 34 34 | 178 18 6 |
| 2 6 8 | 7 1 9 | 3 5 4 |
| 137 137 4 | 8 6 5 | 127 12 9 |
+-------------+-----------+--------------+
| 13 9 5 | 4 8 12 | 6 7 123 |
| 4 123 6 | 9 7 12 | 128 1238 5 |
| 17 8 27 | 3 5 6 | 4 9 12 |
+-------------+-----------+--------------+
| 8 3457 37 | 15 2 134 | 9 6 13 |
| 9 234 1 | 6 34 7 | 5 234 8 |
| 6 2345 23 | 15 9 8 | 12 1234 7 |
+-------------+-----------+--------------+
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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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| Posted: Thu Oct 11, 2007 2:39 am Post subject: Oct 10 VH |
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cgordon,
You can clean up boxes 7 and 8 with basic moves.
Then an x-y wing pivoted on R9C7 should open the puzzle.
Earl |
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TKiel
Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI
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| Posted: Thu Oct 11, 2007 10:54 am Post subject: |
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| Earl wrote: | | I used a finned X-wing on the 1's in R67, C49 TWICE to eliminate the 1's in R7C6 and R9C4. Is that legitimate? |
No.
The fin is r7c6. Either the fin is true or the X-wing is true, which allows one to exclude the 1 in r9c4. The fin can't be excluded in a finned fish. |
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duffy
Joined: 13 Sep 2007
Posts: 26
Location: Toronto Canada
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| Posted: Thu Oct 11, 2007 12:17 pm Post subject: |
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Tracy, I agree that | Code: | ...The fin can't be excluded in a finned fish.
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However, isn't the 1 at r9c4 a fin for a "different" fish with the same corners in r67?
Don D. |
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PouLeeps
Joined: 19 Jun 2007
Posts: 6
Location: Lismore, Australia
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| Posted: Thu Oct 11, 2007 12:21 pm Post subject: |
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| sdq_pete wrote: | Following the basic eliminations I reached the position as given by Johan.
I then found a surprisingly long sequence of 'X' moves, namely:
XYZ 134 R7C6
XY 123 R9C7
CX 3 C34
XY 123 R6C3
XY 123 R6C9
(where my shorthand gives the technique, the digits involved and the pivot, or, in the case of the X-wing, CX for "column X-wing", C34 on columns 3 and 4)
The position after all this was:
| Code: |
+-----------+------------+------------+
| 5 17 9 | 2 34 34 | 178 18 6 |
| 2 6 8 | 7 1 9 | 3 5 4 |
| 13 137 4 | 8 6 5 | 127 12 9 |
+-----------+------------+------------+
| 13 9 5 | 4 8 12 | 6 7 23 |
| 4 123 6 | 9 7 123 | 18 138 5 |
| 7 8 23 | 13 5 6 | 4 9 12 |
+-----------+------------+------------+
| 8 45 7 | 15 2 134 | 9 6 13 |
| 9 234 1 | 6 34 7 | 5 234 8 |
| 6 245 23 | 135 9 8 | 12 124 7 |
+-----------+------------+------------+
|
at which point I needed to resort to "non-standard" logic i.e. non-X-moves. Observing the 12 candidate pairs in blocks 3, 6 and 9, I noticed that whatever value R9C7 took, R6C9 must be 1. Intuitively, I suspect this is related to Johan's links. But can anyone identify any further x-moves here?
Peter |
Pete,
Another xy wing 123 pivot r4c9 should finish it off. |
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sdq_pete
Joined: 30 Apr 2007
Posts: 119
Location: Rotterdam, NL
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| Posted: Thu Oct 11, 2007 1:34 pm Post subject: |
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Ah, yet another XY 123! I should have spotted that whilst I was on my roll. Thanks "PouLeeps" in the antipodes.
Peter |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Thu Oct 11, 2007 7:26 pm Post subject: |
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| Quote: | You can clean up boxes 7 and 8 with basic moves.
Then an x-y wing pivoted on R9C7 should open the puzzle. |
Actually I had cleaned up boxes 7 and 8 in my pencil version - just had trouble cleaning up posted grid. Anyhow, I arrived at this - but still can't see any wings or solution.
| Code: |
+-----------+------------+-------+
| 5 17 9 | 2 34 34 | 178 18 6 |
| 2 6 8 | 7 1 9 | 3 5 4 |
| 137 137 4 | 8 6 5 | 127 12 9 |
+-----------+----------+----------+
| 13 9 5 | 4 8 12 | 6 7 123|
| 4 123 6 | 9 7 12 | 18 138 5 |
| 17 8 27 | 3 5 6 | 4 9 12 |
+-----------+----------+----------+
| 8 457 37 |15 2 34 | 9 6 13 |
| 9 24 1 | 6 34 7 | 5 234 8 |
| 6 245 23 |15 9 8 |12 124 7 |
+-----------+----------+----------+
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duffy
Joined: 13 Sep 2007
Posts: 26
Location: Toronto Canada
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| Posted: Thu Oct 11, 2007 9:39 pm Post subject: |
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Hi cgordon,
Using your grid: the xy-wing you just quoted (but haven't seen in detail yet) "pivoted on R9C7" uses pincers at r6c9, r9c3; this removes the 3 at r7c3. From there your grid solves easily. I'm sure you would have seen it eventually!
Don D. |
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duffy
Joined: 13 Sep 2007
Posts: 26
Location: Toronto Canada
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| Posted: Thu Oct 11, 2007 9:52 pm Post subject: |
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Sorry, "uses pincers at r6c9..." should read "uses pincers at r7c9...".
Don D. |
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TKiel
Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI
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| Posted: Thu Oct 11, 2007 10:16 pm Post subject: |
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| duffy wrote: | | However, isn't the 1 at r9c4 a fin for a "different" fish with the same corners in r67? |
Depends on the grid to which you refer. I was looking at the grid that Johan has in his first post, in which case it's not true. In one of the grids posted later (by Peter, I think) it would be. |
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TKiel
Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI
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| Posted: Thu Oct 11, 2007 10:24 pm Post subject: |
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Johan,
In your B grid from your second post, you end up with 2 +'s in the same box. If + means = 1, how can this be? |
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duffy
Joined: 13 Sep 2007
Posts: 26
Location: Toronto Canada
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| Posted: Thu Oct 11, 2007 10:37 pm Post subject: |
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Tracy,
I was looking at sdq_pete's grid, just before my first post here.
Don D. |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Thu Oct 11, 2007 11:07 pm Post subject: |
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| Quote: | | I'm sure you would have seen it eventually! |
Duffy: Wannna bet? Thank you anyway. I still think this was an extra difficult one when the discussions involve fins and fish. |
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