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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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 Posted: Thu Oct 21, 2021 1:10 pm Post subject: All Hail Danny (4) |
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| Code: | +-----------------------+
| . 8 . | . . 9 | 4 1 . |
| 4 3 . | 6 . 1 | . . 9 |
| . . . | . . 4 | . . 6 |
|-------+-------+-------|
| . 7 . | 9 . 3 | . . . |
| . . . | . 8 . | . . 1 |
| 3 4 8 | 1 . . | 9 . . |
|-------+-------+-------|
| 8 . . | . . 2 | 6 . 5 |
| 6 . . | . . . | . . . |
| . 1 7 | . 9 . | 8 . . |
+-----------------------+ |
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dongrave
Joined: 06 Mar 2014
Posts: 568
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| Posted: Fri Oct 22, 2021 4:07 pm Post subject: |
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Thanks for the puzzle Mohulmeister! Here's the grid after basics:
| Code: | +--------------+--------------+-----------------+
| 7 8 6 | 235 235 9 | 4 1 23 |
| 4 3 25 | 6 27 1 | 257 8 9 |
| 19 25 19 | 8 237 4 | 2357 2357 6 |
+--------------+--------------+-----------------+
| 125 7 125 | 9 46 3 | 25 46 8 |
| 259 6 259 | 24 8 57 | 2357 23457 1 |
| 3 4 8 | 1 26 57 | 9 2567 27 |
+--------------+--------------+-----------------+
| 8 9 34 | 347 1 2 | 6 37 5 |
| 6 25 34 | 3457 345 8 | 1 9 2347 |
| 25 1 7 | 345 9 6 | 8 23 234 |
+--------------+--------------+-----------------+
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Then I used chain that started with a 2 in r2c3 that visited almost every unsolved cell! Ha! |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Fri Oct 22, 2021 9:24 pm Post subject: |
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Well done dongrave!
Was it a relative of this one ?
-2r1c4=r5c4-r6c5=r6c89-(2=5)r4c7-(5)r56c8=r3c8-r3c2=r8c2-r8c5=r1c5 means r1c4<>5 and r1c5<>2 |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Sat Oct 23, 2021 9:38 am Post subject: |
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There is also an interesting situation when we start with a 7 (not 5) in r6c6
(5=7)r6c6-(7=2)r6c9-(2=5)r4c7-(5)r6c8
So when we remove 5 from r6c6 and follow the chain above, the 5 in r6c8 is also removed leaving no 5's in row 6. So r6c6 is not 7 but must equal 5. |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Sat Oct 23, 2021 9:59 am Post subject: |
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| Problem is, it doesn't make much of a dent in the puzzle! |
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Clement
Joined: 24 Apr 2006
Posts: 1111
Location: Dar es Salaam Tanzania
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| Posted: Sat Oct 23, 2021 10:15 am Post subject: All Hail Danny (4) |
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I have to settle for three steps | Code: |
+------------------+---------------------+------------------------+
| 7 8 6 |b235 b235 9 | 4 1 c23 |
| 4 3 i25 | 6 a27 1 |j25-7 8 9 |
| 19 h25 19 | 8 237 4 | 2357 2357 6 |
+------------------+---------------------+------------------------+
| 125 7 125 | 9 46 3 | 25 46 8 |
| 259 6 259 | 24 8 57 | 2357 23457 1 |
| 3 4 8 | 1 26 57 | 9 2567 d27 |
+------------------+---------------------+------------------------+
| 8 9 34 | 347 1 2 | 6 37 5 |
| 6 g25 34 | 3457 345 8 | 1 9 d2347 |
|f25 1 7 | 345 9 6 | 8 e23 d234 |
+------------------+---------------------+------------------------+
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Step 1: (7=2)r2c5 r1c45 = r1c9 (2=74|3)r689c9 (3=2)r9c8 (2=5)r9c1 r8c2 = r3c2 r2c3 = (5)r2c7 => - 7r2c7
| Code: |
+--------------------+---------------------+-----------------------+
| 7 8 6 | 235 235 9 | 4 1 23 |
| 4 3 d25 | 6 7 1 |e25 8 9 |
| 19 c25 19 | 8 23 4 | 37 2357 6 |
+------------+-------------+---------------+
| 125 7 125 | 9 46 3 | f25 46 8 |
| 259 6 259 | 24 8 57 | 37 23457 1 |
| 3 4 8 | 1 26 57 | 9 2567 7-2 |
+--------------------+---------------------+-----------------------+
| 8 9 34 | 347 1 2 | 6 37 5 |
| 6 b25 34 | 3457 345 8 | 1 9 a2347 |
| 25 1 7 | 345 9 6 | 8 23 234 |
+--------------------+---------------------+-----------------------+
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Step 2: (2)r8c9 = r8c2 r3c2 = r2c3 r2c7 = (2)r4c7 => - 2r6c9
| Code: |
+--------------------+-------------------+----------------------+
| 7 8 6 | 235 235 9 | 4 1 23 |
| 4 3 25 | 6 7 1 | 25 8 9 |
| 19 b25 19 | 8 23 4 | 7 c235 6 |
+--------------------+-------------------+----------------------+
| 125 7 125 | 9 46 3 | 25 46 8 |
| 259 6 259 |e24 8 7 | 3 d245 1 |
| 3 4 8 | 1 26 5 | 9 26 7 |
+--------------------+-------------------+----------------------+
| 8 9 34 |f34 1 2 | 6 7 5 |
| 6 a25 34 | 7 g34-5 8 | 1 9 234 |
| 25 1 7 |f345 9 6 | 8 23 234 |
+--------------------+-------------------+----------------------+
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Step 3: (5)r8c2 = r3c2 r3c8 = (5-4)r5c8 = r5c4 r79c4 = (4)r8c5 => - 5r8c5; stte |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Sat Oct 23, 2021 10:53 am Post subject: |
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| Very Nice Clement |
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dongrave
Joined: 06 Mar 2014
Posts: 568
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| Posted: Sat Oct 23, 2021 12:25 pm Post subject: |
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| Mogulmeister wrote: | Well done dongrave!
Was it a relative of this one ?
-2r1c4=r5c4-r6c5=r6c89-(2=5)r4c7-(5)r56c8=r3c8-r3c2=r8c2-r8c5=r1c5 means r1c4<>5 and r1c5<>2 |
Thanks Mogulmeister! No, yours is much simpler. Mine started with a 2 in r2c3 and went around the grid and ended up with a 7 in both r7c4 and r7c8!
Nice puzzle Mogulmeister! wow! Great job Clement! |
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dongrave
Joined: 06 Mar 2014
Posts: 568
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| Posted: Sat Oct 23, 2021 4:48 pm Post subject: |
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I found a slightly shorter chain than my original one.
2*r2c3-(2=7)r2c5-(27=5)r2c7-(5=2)r4c7-(2=1|5)r4c13-(2*5=9)r5c3-(59=2)r5c1-[(2=4*)r5c4 -(2=5)r9c1]-(4*5=3)r9c4-(34*=7)r7c4-r8c4=r8c9-(7=2)r6c9-(2=6)r6c5-(6=4)r4c5 contradiction (i.e. 4r5c4, 4r4c5) => r2c3<> 2; stte. Whew! |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Sun Oct 24, 2021 10:25 am Post subject: |
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So heres a sideways look.
Theres an ANP <25> at r2c5 and r2c7.
If ANP is TRUE (5=27)r2c57 then R2c3 < > 2 and puzzle is solved.
-OR-
If ANP is FALSE (27=5)r2c57 then
(27=5)r2c57-(5=2)r4c7-(2=15)r4c13-(5=29)r5c13-(2=4)r5c4
R5c4 = 4 and puzzle is solved
You could extend this chain further, which will eventually produce contradictions in block 1 (two 2's) showing that r2c7 < > 5
Last edited by Mogulmeister on Sun Oct 24, 2021 1:00 pm; edited 7 times in total |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Sun Oct 24, 2021 10:27 am Post subject: |
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| dongrave wrote: | I found a slightly shorter chain than my original one.
2*r2c3-(2=7)r2c5-(27=5)r2c7-(5=2)r4c7-(2=1|5)r4c13-(2*5=9)r5c3-(59=2)r5c1-[(2=4*)r5c4 -(2=5)r9c1]-(4*5=3)r9c4-(34*=7)r7c4-r8c4=r8c9-(7=2)r6c9-(2=6)r6c5-(6=4)r4c5 contradiction (i.e. 4r5c4, 4r4c5) => r2c3<> 2; stte. Whew! |
Whew! Shorter ? Amazing chain! Two contradictory 4's in block 5. |
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TomC
Joined: 30 Oct 2020
Posts: 358
Location: Wales
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| Posted: Sun Oct 24, 2021 1:51 pm Post subject: |
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After basics
| Code: |
+------------+--------------+-----------------+
| 7 8 6 | 235 235 9 | 4 1 23 |
| 4 3 25 | 6 27 1 | 257 8 9 |
| 19 25 19 | 8 237 4 | 2357 2357 6 |
+------------+--------------+-----------------+
| 125 7 125 | 9 46 3 | 25 46 8 |
| 259 6 259 | 24 8 57 | 2357 23457 1 |
| 3 4 8 | 1 26 57 | 9 2567 27 |
+------------+--------------+-----------------+
| 8 9 34 | 347 1 2 | 6 37 5 |
| 6 25 34 | 3457 3457 8 | 1 9 2347 |
| 25 1 7 | 345 9 6 | 8 23 234 |
+------------+--------------+-----------------+
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Play this puzzle online at the Daily Sudoku site
One way to simplify this puzzle is to notice that if r1c9 =2 then using box 2 and 9 you would end up with no 2's in row 6
Still not solved but much easier
edit basics fixed (I hope!)
Last edited by TomC on Sun Oct 24, 2021 2:36 pm; edited 2 times in total |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Sun Oct 24, 2021 2:07 pm Post subject: |
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| Nice one Tom. Agreed. |
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