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ZeroAssoluto
Joined: 05 Feb 2017 Posts: 872 Location: Rimini, Italy
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Posted: Thu Jun 09, 2022 10:12 am Post subject: Jun 09 VH |
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Hi everyone,
Code: |
+-----------+------------+----------------+
| 5 13 7 | 12 4 6 | 123 8 9 |
| 4 139 2 | 8 139 5 | 13 7 6 |
| 6 8 139 | 7 1239 23 | 4 1235 135 |
+-----------+------------+----------------+
| 9 2 18 | 36 5 4 | 1368 136 7 |
| 3 6 58 | 12 12 7 | 58 9 4 |
| 7 145 145 | 36 8 9 | 1356 1356 2 |
+-----------+------------+----------------+
| 2 34 6 | 5 7 1 | 9 34 8 |
| 8 359 359 | 4 236 23 | 7 12356 135 |
| 1 7 345 | 9 236 8 | 2356 23456 35 |
+-----------+------------+----------------+
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Play this puzzle online at the Daily Sudoku site
Quote: | In one step
Swordfish with number 3 in r389c369 and -3 in r3c58,r8c258,r9c578
or
XY-Wing 1,2,3 in r1c24,r3c6 and -3 in r3c3
and L.C. in c2 |
Ciao Gianni |
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Earl
Joined: 30 May 2007 Posts: 677 Location: Victoria, KS
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Posted: Thu Jun 09, 2022 11:33 am Post subject: Jun06VH |
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If basics are used first, the 123xywing should do it.
Early Earl |
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ZeroAssoluto
Joined: 05 Feb 2017 Posts: 872 Location: Rimini, Italy
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Posted: Fri Jun 10, 2022 9:23 am Post subject: |
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If you don't delete number 3 from r3c3 (with the XY-Wing) you don't have the LC in column 2 with number 3.
Ciao Gianni |
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TomC
Joined: 30 Oct 2020 Posts: 349 Location: Wales
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Posted: Fri Jun 10, 2022 11:44 am Post subject: |
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Or you could say a=4 to solve
Code: |
+------------+---------------+----------------+
| 5 b13 7 | c12 4 6 | 123 8 9 |
| 4 139 2 | 8 139 5 | 13 7 6 |
| 6 8 139 | 7 1239 d23 | 4 1235 135 |
+------------+---------------+----------------+
| 9 2 18 | 36 5 4 | 1368 136 7 |
| 3 6 58 | 12 12 7 | 58 9 4 |
| 7 145 145 | 36 8 9 | 1356 1356 2 |
+------------+---------------+----------------+
| 2 a34 6 | 5 7 1 | 9 34 8 |
| 8 359 359 | 4 236 23 | 7 12356 135 |
| 1 7 345 | 9 236 8 | 2356 23456 35 |
+------------+---------------+----------------+
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If a=3, b=1, c=2, d=3 leads to no <3> in box 1 |
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Mogulmeister
Joined: 03 May 2007 Posts: 1151
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Posted: Sat Jun 11, 2022 2:39 pm Post subject: |
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Picking up a little on all these themes there is another structure that gets us to the same conclusion as Tom’s contradiction.
Using Tom’s grid, incorporating a, is an ANP <139> at r12c2.
If ANP is true then the <13> pair eliminates the <3> at a making a = 4
If ANP is false then r2c2 = 9 which creates an XY wing with c and d.
This makes b = 3 and this makes a = 4.
Last edited by Mogulmeister on Tue Jun 14, 2022 3:22 pm; edited 1 time in total |
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Mogulmeister
Joined: 03 May 2007 Posts: 1151
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Posted: Sat Jun 11, 2022 6:47 pm Post subject: |
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ZeroAssoluto wrote: | If you don't delete number 3 from r3c3 (with the XY-Wing) you don't have the LC in column 2 with number 3.
Ciao Gianni |
….but Earl’s <123> XY at bcd is sufficient to remove the 3 from r3c3. This means the 3’s in col 2 mean a = 4 |
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TomC
Joined: 30 Oct 2020 Posts: 349 Location: Wales
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Posted: Sat Jun 11, 2022 8:20 pm Post subject: |
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I think it's always good to look at solutions in different ways.
The ANP by Mogulmeister could also be looked at as:
In box 1 it doesn't matter where you put <9> "a" is always <4> |
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Mogulmeister
Joined: 03 May 2007 Posts: 1151
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Posted: Sat Jun 11, 2022 8:38 pm Post subject: |
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That’s right. Thanks Tom. Should have made that explicit. Whether ANP true or false or wherever the 9, the answer is that “a” is always 4 |
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ZeroAssoluto
Joined: 05 Feb 2017 Posts: 872 Location: Rimini, Italy
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Posted: Sun Jun 12, 2022 10:08 am Post subject: |
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Mogulmeister wrote: | ZeroAssoluto wrote: | If you don't delete number 3 from r3c3 (with the XY-Wing) you don't have the LC in column 2 with number 3.
Ciao Gianni |
….but Earl’s <123> XY at bcd is sufficient to remove the 3 from r3c3. This means the 3’s in col 2 mean a = 4 |
I said first XY-Wing then LC
Earl said first basic
I don't see basic as first step
Ciao Gianni |
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Mogulmeister
Joined: 03 May 2007 Posts: 1151
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Posted: Sun Jun 12, 2022 10:35 am Post subject: |
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I think the basic must come after the <123> ?
Once you have removed the 3 from r3c3 it is just basics. |
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ZeroAssoluto
Joined: 05 Feb 2017 Posts: 872 Location: Rimini, Italy
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Posted: Sun Jun 12, 2022 12:25 pm Post subject: |
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When I talk about basics I am talking about the simplest techniques (LC, Pairs, Triples).
In this case I think LC should come after XY-Wing, not before, not as the first step. |
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Mogulmeister
Joined: 03 May 2007 Posts: 1151
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Posted: Sun Jun 12, 2022 2:13 pm Post subject: |
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Yes that is also what I was saying. I think Earl may have meant to say xy wing and then “btte.” I think we note basics but don’t regard them as a step as the eliminations are implicit. |
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