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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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 Posted: Sat Sep 29, 2007 11:35 am Post subject: DB Saturday Puzzle: September 29, 2007 |
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| Code: | Puzzle: DB092907 ******
+-------+-------+-------+
| . . . | 6 1 . | . 9 . |
| 6 . . | . . . | . 2 3 |
| . 5 . | . 3 . | 4 . 8 |
+-------+-------+-------+
| . . 2 | . 7 1 | . . 4 |
| . . . | . . . | . . . |
| 1 . . | 3 9 . | 7 . . |
+-------+-------+-------+
| 4 . 3 | . 2 . | . 7 . |
| 2 9 . | . . . | . . 1 |
| . 1 . | . 4 8 | . . . |
+-------+-------+-------+ |
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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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| Posted: Sat Sep 29, 2007 2:37 pm Post subject: Saturday DB Sept 29 |
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After basics, a skyscraper (-5), an x-y chain (-5) and the puzzle was reduced to singles.
Earl |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Sep 29, 2007 4:04 pm Post subject: |
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The basics get me here: | Code: | +----------------+----------------+----------------+
| 3 2 8 | 6 1 4 | 5 9 7 |
| 6 47 479 | 589 58 579 | 1 2 3 |
| 79 5 1 | 2 3 79 | 4 6 8 |
+----------------+----------------+----------------+
| 589 36 2 | 58 7 1 | 369 35 4 |
| 5789 367 579 | 4 568 256 | 2369 1 2569 |
| 1 46 45 | 3 9 256 | 7 8 256 |
+----------------+----------------+----------------+
| 4 8 3 | 1 2 569 | 69 7 569 |
| 2 9 567 | 57 56 3 | 8 4 1 |
| 57 1 567 | 579 4 8 | 2369 35 2569 |
+----------------+----------------+----------------+
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I can see nothing but chains.
Keith |
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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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| Posted: Sat Sep 29, 2007 4:20 pm Post subject: Saturday DB Sept 29 |
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Keith,
I used an x-y chain to eliminate 5's from R4C1 and R6C9, which built a skyscraper in C1C8, eliminating the 5 from R5C9. Then just singles.
I think.
Earl |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat Sep 29, 2007 4:31 pm Post subject: |
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| My grid is identical to Keith's and I can't find a logical move. |
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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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| Posted: Sat Sep 29, 2007 5:48 pm Post subject: Saturday DB Sept 29 |
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Marty,
There is an x-y chain from R6C3 to R4C8 with a 5 pincer eliminating 5's from R4C1 and R6C9. That clears a skyscraper of 5's in C1 and C8, which eliminates the the 5 from R5C9. The rest is straight forward.
Earl |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat Sep 29, 2007 9:45 pm Post subject: |
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Earl,
Kudos for finding that solution. |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Sat Sep 29, 2007 10:39 pm Post subject: |
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I too saw that XY Chain. But then, instead of the Skyscraper, I used ERs for the next step. (Because of so much recent interest here in ERs, I am on the lookout for them.)
In this case, we use the strong link on <5> in R6C36 and the 3 ERs in Boxes 7, 9 and 6. R4C4 can "see" R6C6 directly and R6C3 via the 3 ERs. Thus, the <5> in R4C4 is eliminated. |
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TKiel
Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI
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| Posted: Sun Sep 30, 2007 4:03 pm Post subject: |
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After the XY-chain, falling somewhere between the multi-coloring with two chains used by Earl and the grouped coloring used by Asellus, is a multi-coloring with three chains.
| Code: |
*-----------------------------------------------------------*
| 3 2 8 | 6 1 4 | 5 9 7 |
| 6 47 479 | 589 58 579 | 1 2 3 |
| 79 5 1 | 2 3 79 | 4 6 8 |
|-------------------+-------------------+-------------------|
| 89 36 2 | 58 7 1 | 369 35 4 |
| 5789a 367 579 | 4 568 256 | 2369 1 2569 |
| 1 46 45B | 3 9 256b | 7 8 26 |
|-------------------+-------------------+-------------------|
| 4 8 3 | 1 2 569c | 69 7 569C |
| 2 9 567 | 57 56 3 | 8 4 1 |
| 57A 1 567 | 579 4 8 | 2369 35 2569 |
*-----------------------------------------------------------*
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TKiel
Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI
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| Posted: Sun Sep 30, 2007 8:57 pm Post subject: |
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| Quote: | | The basics get me here...I can see nothing but chains. |
| Quote: | | My grid is identical...I can't find a logical move. |
Why do we consider an XY-wing a satisfactory move but an XY-chain as less than logical and something to be used only when there is nothing else? |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sun Sep 30, 2007 11:43 pm Post subject: |
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| TKiel wrote: | | Quote: | | The basics get me here...I can see nothing but chains. |
| Quote: | | My grid is identical...I can't find a logical move. |
Why do we consider an XY-wing a satisfactory move but an XY-chain as less than logical and something to be used only when there is nothing else? |
I don't know if I gave a different impression, but I'm fine with XY-Chains. Unfortunately, I didn't catch this one. |
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Johan
Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium
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| Posted: Mon Oct 01, 2007 12:24 am Post subject: |
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| Quote: |
Why do we consider an XY-wing a satisfactory move but an XY-chain as less than logical and something to be used only when there is nothing else? |
Perhaps xy-wings are easier to spot, because only 3 cells are involved, xy-chains using more than 5 cells are a little more harder to detect and are often called a cumbersome way, it looks like T&E(not IMO) when using seven, eight, nine ore more intermediate bivalue links, leading you to the two pincer cells, eliminating the common pincer cell digit for solving the puzzle.
Nevertheless Tracy is right about this topic, when nothing else is found the "inferior" logical step becomes the superior solving step. |
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TKiel
Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI
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| Posted: Mon Oct 01, 2007 9:01 pm Post subject: |
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| Quote: | | the "inferior" logical step becomes the superior solving step. |
Nicely phrased. Has a poetic ring to it.
I know I spent a lot of time trying to find something other than the XY-chain that Earl said he used and I'm also not one who thinks of them as T&E. |
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