dailysudoku.com Forum Index dailysudoku.com
Discussion of Daily Sudoku puzzles
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

chicago tribune 2/16/18 DS too hard, BUG+1?

 
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Other puzzles
View previous topic :: View next topic  
Author Message
mtharp



Joined: 19 Jun 2006
Posts: 30

PostPosted: Sun Feb 18, 2018 6:03 pm    Post subject: chicago tribune 2/16/18 DS too hard, BUG+1? Reply with quote

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
Back to top
View user's profile Send private message
Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Sun Feb 18, 2018 6:24 pm    Post subject: Reply with quote

Mike,

No time now for longer reply. It's a BUG+3.
Back to top
View user's profile Send private message
Aj Dimonios



Joined: 01 May 2017
Posts: 326
Location: Sassari Italy

PostPosted: Sun Feb 18, 2018 8:45 pm    Post subject: Reply with quote

Hi everyone

[(5-7)R2C1=7R2C2-(7=2)R8C2-2R8C9 and 5R2C1-5R3C1=5R3C4-(5=3)R8C4-3R8C9]=>contradiction R8C9==>-5R2C1=>solution.

Ciao a Tutti
Paolo
Back to top
View user's profile Send private message
Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Sun Feb 18, 2018 10:14 pm    Post subject: Reply with quote

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
Back to top
View user's profile Send private message
keith



Joined: 19 Sep 2005
Posts: 3340
Location: near Detroit, Michigan, USA

PostPosted: Tue Feb 20, 2018 7:38 am    Post subject: Re: chicago tribune 2/16/18 DS too hard, BUG+1? Reply with quote

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
Back to top
View user's profile Send private message
Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Wed Feb 21, 2018 1:07 am    Post subject: Reply with quote

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.
Back to top
View user's profile Send private message
keith



Joined: 19 Sep 2005
Posts: 3340
Location: near Detroit, Michigan, USA

PostPosted: Wed Feb 21, 2018 4:01 am    Post subject: Reply with quote

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
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Other puzzles All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group