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mtharp
Joined: 19 Jun 2006
Posts: 30
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 Posted: Sun Feb 18, 2018 6:03 pm Post subject: chicago tribune 2/16/18 DS too hard, BUG+1? |
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Folks, I believe this is a BUG+1, with the extra candidate being 9 in column 5 and in box 8. However, there is an extra candidate (7) in row 8. I chose 9 for r8c5 and reached a solution.
Keith, your comments, in particular, solicited.
| Code: |
+-----------+-----------+---------+
| 8 1 2 | 9 4 7 | 5 3 6 |
| 57 67 9 | 1 3 56 | 2 4 8 |
| 45 46 3 | 56 8 2 | 9 1 7 |
+-----------+-----------+---------+
| 3 8 7 | 2 59 59 | 1 6 4 |
| 6 9 4 | 8 7 1 | 3 2 5 |
| 2 5 1 | 4 6 3 | 7 8 9 |
+-----------+-----------+---------+
| 147 247 5 | 36 19 69 | 8 79 23 |
| 17 27 6 | 35 159 8 | 4 79 23 |
| 9 3 8 | 7 2 4 | 6 5 1 |
+-----------+-----------+---------+
|
Play this puzzle online at the Daily Sudoku site
Mike |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sun Feb 18, 2018 6:24 pm Post subject: |
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Mike,
No time now for longer reply. It's a BUG+3. |
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Ajò Dimonios
Joined: 01 May 2017
Posts: 339
Location: Sassari Italy
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| Posted: Sun Feb 18, 2018 8:45 pm Post subject: |
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Hi everyone
[(5-7)R2C1=7R2C2-(7=2)R8C2-2R8C9 and 5R2C1-5R3C1=5R3C4-(5=3)R8C4-3R8C9]=>contradiction R8C9=Ø=>-5R2C1=>solution.
Ciao a Tutti
Paolo |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sun Feb 18, 2018 10:14 pm Post subject: |
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| Code: | +-----------+-----------+---------+
| 8 1 2 | 9 4 7 | 5 3 6 |
| 57 67 9 | 1 3 56 | 2 4 8 |
| 45 46 3 | 56 8 2 | 9 1 7 |
+-----------+-----------+---------+
| 3 8 7 | 2 59 59 | 1 6 4 |
| 6 9 4 | 8 7 1 | 3 2 5 |
| 2 5 1 | 4 6 3 | 7 8 9 |
+-----------+-----------+---------+
| 147 247 5 | 36 19 69 | 8 79 23 |
| 17 27 6 | 35 159 8 | 4 79 23 |
| 9 3 8 | 7 2 4 | 6 5 1 |
+-----------+-----------+---------+ |
Sure looks like a BUG+3, but I can't play it as such because I don't have a candidate for r7c2 or r8c5.
Deadly Pattern (79-19-17)r78c158
4r7c1=5r8c5
4r7c1-(4=576)r23c1,r2c2
5r8c5-(5=327)r8c492-(7=6)r2c2=> r2c2=6 |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Tue Feb 20, 2018 7:38 am Post subject: Re: chicago tribune 2/16/18 DS too hard, BUG+1? |
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Mike,
I solved this puzzle a couple of days ago, but I forget where I found it. Maybe it was the Friday Detroit Free Press / LA Times puzzle?
In a BUG+N, N is the number of cells that have more than two candidates. So, this is potentially a BUG+3.
When you look at rows, columns, and boxes that contain an N cell, the question is, what choice(s) will avoid the BUG pattern? The BUG is a situation where the cells all have two candidates, and each candidate occurs twice.
When you do this, the condition is OR. It is not sufficient to find one BUG buster, you have to consider them all and find a common outcome.
So, the BUG-N cells are R7C1, R7C2, R8C5.
You need to look at C125, R78, and B78.
C1: 57 45 17 147; The BUG buster is R7C1=7
C2: 67 46 27 247; The BUG buster is R7C2=7
C5: 59 19 159; The BUG buster is R8C5=9
B8 is also R8C5=9
For the others the situation is more murky. I may be skating on thin ice here.
From the columns and B8 I concluded one of R7C12=7, or R8C5=9.
The common outcome is R7C8=9, R8C8=7.
I then verified that these choices eliminate a BUG pattern in R78 and B7.
I believe this is valid logic. But, maybe some Sudoku theorist will come along to beat me with a stick.
Keith
| mtharp wrote: | Folks, I believe this is a BUG+1, with the extra candidate being 9 in column 5 and in box 8. However, there is an extra candidate (7) in row 8. I chose 9 for r8c5 and reached a solution.
Keith, your comments, in particular, solicited.
| Code: |
+-----------+-----------+---------+
| 8 1 2 | 9 4 7 | 5 3 6 |
| 57 67 9 | 1 3 56 | 2 4 8 |
| 45 46 3 | 56 8 2 | 9 1 7 |
+-----------+-----------+---------+
| 3 8 7 | 2 59 59 | 1 6 4 |
| 6 9 4 | 8 7 1 | 3 2 5 |
| 2 5 1 | 4 6 3 | 7 8 9 |
+-----------+-----------+---------+
| 147 247 5 | 36 19 69 | 8 79 23 |
| 17 27 6 | 35 159 8 | 4 79 23 |
| 9 3 8 | 7 2 4 | 6 5 1 |
+-----------+-----------+---------+
|
Play this puzzle online at the Daily Sudoku site
Mike |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Wed Feb 21, 2018 1:07 am Post subject: |
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| Quote: | C1: 57 45 17 147; The BUG buster is R7C1=7
C2: 67 46 27 247; The BUG buster is R7C2=7
C5: 59 19 159; The BUG buster is R8C5=9
B8 is also R8C5=9 |
Keith, I'll assume you're correct, as usual, but I'd like to know where I'm wrong.
I thought the BUG killer had to have three occurrences in row, column and box. So r8c5 doesn't qualify since there are not three 9s in r8.
The 7s in r7c12 are the obvious choice as they meet the requirement of three occurrences in three houses. However, I've been under the assumption that with two killers in a house, such as the 7s in r7c12, there had to be four occurrences in that house and there are not four 7s in r7.
We're removing numbers that if not present, would leave the BUG pattern. Removing the 7s from r7c12 would not leave bivalues in r7 and only one 7. |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Wed Feb 21, 2018 4:01 am Post subject: |
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Marty,
I don't know. I found the BUG busters in the columns, and then noted that they solve the puzzle. To be more precise, I found the BUG busters all had a common outcome in solving R78C8.
Keith |
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