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immpy
Joined: 06 May 2017
Posts: 571
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 Posted: Sun Sep 05, 2021 4:15 pm Post subject: VH+ 090521 |
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Hello all, enjoy the puzzle...
| Code: |
+-------+-------+-------+
| . . 3 | 6 . 5 | 7 . 1 |
| 6 . 7 | 8 . . | 4 . 2 |
| 8 1 . | . 3 . | 9 5 6 |
+-------+-------+-------+
| . . . | 7 . 3 | . . . |
| . . 1 | . . . | 6 . . |
| . . . | 9 . 4 | . . . |
+-------+-------+-------+
| 3 2 . | . 8 6 | 1 7 9 |
| 1 . 9 | . . . | 5 . 8 |
| . . 6 | 1 . 9 | 2 . . |
+-------+-------+-------+
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Play this puzzle online at the Daily Sudoku site
cheers...immp |
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Clement
Joined: 24 Apr 2006
Posts: 1111
Location: Dar es Salaam Tanzania
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| Posted: Sun Sep 05, 2021 7:40 pm Post subject: VH+090521 |
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| Code: |
+-----------------------+-------------------+------------------+
|f249 49 3 | 6 g2-4 5 | 7 8 1 |
| 6 5 7 | 8 9 1 | 4 3 2 |
| 8 1 24 | 24 3 7 | 9 5 6 |
+-----------------------+-------------------+------------------+
| 2459 b469 245 | 7 c16 3 | 8 c12 45|
| 47 3 1 | 25 25 8 | 6 9 47|
|e257 b67 8 | 9 16 4 | 3 d12 57|
+-----------------------+-------------------+------------------+
| 3 2 45 | 45 8 6 | 1 7 9 |
| 1 b47 9 | 3 a47 2 | 5 6 8 |
| 57 8 6 | 1 57 9 | 2 4 3 |
+-----------------------+-------------------+------------------+
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(4)r8c5 = (476)r864c2 - (6=2)r4c58 - r6c8 = r6c1 - r1c1 = (2)r1c5 => - 4r1c5; stte |
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TomC
Joined: 30 Oct 2020
Posts: 358
Location: Wales
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| Posted: Mon Sep 06, 2021 5:48 am Post subject: |
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| Code: |
+--------------+---------+---------+
| 249 49 3 | 6 24 5 | 7 8 1 |
| 6 5 7 | 8 9 1 | 4 3 2 |
| 8 1 24 | 24 3 7 | 9 5 6 |
+--------------+---------+---------+
| 2459 469 245 | 7 16 3 | 8 12 45 |
| 47 3 1 | 25 25 8 | 6 9 47 |
| 257 67 8 | 9 16 4 | 3 12 57 |
+--------------+---------+---------+
| 3 2 45 | 45 8 6 | 1 7 9 |
| 1 47 9 | 3 47 2 | 5 6 8 |
| 57 8 6 | 1 57 9 | 2 4 3 |
+--------------+---------+---------+
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Play this puzzle online at the Daily Sudoku site
r5c1 <>7 as then r4c9=5 and r9c1= 5 leads to no 5's in box 4
then a couple of basics reveals a 257 XY wing giving r4c1 and r7c3 <> 5 |
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dongrave
Joined: 06 Mar 2014
Posts: 568
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| Posted: Mon Sep 06, 2021 3:22 pm Post subject: |
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| I used the chain: 7r6c2-[(7=4*)r5c1 -(7=5)r6c9]-(57=2)r6c1-(24*=9)r1c1-(9=4)r1c2-(4=7)r8c2 contradiction => r6c2 <> 7; stte. |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Wed Sep 08, 2021 10:29 am Post subject: |
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This was a well designed puzzle Immp and took some tinkering with. Thank you.
Sorry about the busy diagram (below) but there is a fair bit going on.
Firstly, we have an AALS
Set A (Green) {2,4,5,7,9}
Set B (Beige) {5,7}
Restricted common is 5.
Common Candidate 7 in Red can see the 7’s in A & B and would normally be eliminated. However, the restricted common is banjaxed because there is another 5 in r4c1.
The key here is the yellow square at r4c9 <45>.
If it is 5 then we remove that pesky 5 in r4c1. The ALS XZ now solves the puzzle. R6c2 <> 7.
-OR-
If it is 4 then
(5=4)r4c9-(4=25)r4c3
and at the same time:
(5=4)r4c9=(5)r6c9-(5=27)r6c1
Which forms Tom's previously mentioned <257> XY wing (purple+r6c1) and r4c1 and r7c3 <> 5.
Either route solves. For the sake of completeness the XY wing also removes the 7 (red).
Last edited by Mogulmeister on Tue Oct 19, 2021 10:01 am; edited 11 times in total |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Wed Sep 08, 2021 10:33 am Post subject: |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Wed Sep 08, 2021 11:23 am Post subject: |
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Of course there is a snappier solution but I do like ALS solves !
You can simplify matters by saying that:
If yellow square is 4 then <257> XY Wing in solves
otherwise
If yellow square is 5 then r6c9 = 7 so r6c2 <> 7 solves |
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