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Free Press August 15, 2014

 
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keith



Joined: 19 Sep 2005
Posts: 3179
Location: near Detroit, Michigan, USA

PostPosted: Sat Aug 16, 2014 2:22 pm    Post subject: Free Press August 15, 2014 Reply with quote

Basics are hard!

Code:
Puzzle: FP081514
+-------+-------+-------+
| 1 . 4 | . . . | 8 . . |
| . 8 . | 4 . . | . . 3 |
| . . . | . . 2 | . . 4 |
+-------+-------+-------+
| . . . | . . 5 | . 7 9 |
| . . 3 | . . 7 | 1 . . |
| 7 1 . | 8 . . | . . . |
+-------+-------+-------+
| 4 6 . | 5 . . | . . . |
| 3 . . | . . 9 | . 4 . |
| . . 5 | . . . | 3 . 2 |
+-------+-------+-------+

Play this puzzle online at the Daily Sudoku site

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5166
Location: Rochester, NY, USA

PostPosted: Sat Aug 16, 2014 4:23 pm    Post subject: Reply with quote

Code:

+-----------------+-----------------+---------------+
| 1    23579 4    | 3679  35679 36  | 8    259  67  |
| 2569 8     2679 | 4     15679 16  | 2679 1259 3   |
| 569  3579  679  | 13679 8     2   | 679  159  4   |
+-----------------+-----------------+---------------+
| 268  24    268  | 13    13    5   | 246  7    9   |
| 2569 2459  3    | 269   2469  7   | 1    28   68  |
| 7    1     269  | 8     2469  46  | 246  3    5   |
+-----------------+-----------------+---------------+
| 4    6     128  | 5     23    38  | 79   89   178 |
| 3    27    18   | 267   267   9   | 5    4    18  |
| 89   79    5    | 17    147   148 | 3    6    2   |
+-----------------+-----------------+---------------+

Play this puzzle online at the Daily Sudoku site

On puzzles like this I populate the grid via Draw/Play which greatly minimizes the chance of a mechanical error.

Type 3 UR (18), r78,c39

2r7c3=7r7c9-(7=6)r1c9-(6=8)r5c9-(8=2)r5c8-r5c45=r6c5=>r7c5<>2
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keith



Joined: 19 Sep 2005
Posts: 3179
Location: near Detroit, Michigan, USA

PostPosted: Sat Aug 16, 2014 7:57 pm    Post subject: Reply with quote

There is a slightly simpler chain in R17 that takes out 7 in R7C9 to solve the puzzle. The UR is still needed.

Pincers on 7: 67 36 38 89 79.

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5166
Location: Rochester, NY, USA

PostPosted: Sat Aug 16, 2014 8:11 pm    Post subject: Reply with quote

keith wrote:
There is a slightly simpler chain in R17 that takes out 7 in R7C9 to solve the puzzle. The UR is still needed.

Pincers on 7: 67 36 38 89 79.

Keith


Keith,

I don't understand. The first sentence says the chain solves it and the second says the UR is still needed. Question Question
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keith



Joined: 19 Sep 2005
Posts: 3179
Location: near Detroit, Michigan, USA

PostPosted: Sat Aug 16, 2014 8:15 pm    Post subject: Reply with quote

Marty R. wrote:
keith wrote:
There is a slightly simpler chain in R17 that takes out 7 in R7C9 to solve the puzzle. The UR is still needed.

Pincers on 7: 67 36 38 89 79.

Keith


Keith,

I don't understand. The first sentence says the chain solves it and the second says the UR is still needed. Question Question

Marty, this chain is proposed as an alternative to yours, after the UR is played. However, my chain is also available before the UR, which is then still needed.

Take the steps (chain, UR) in any order. And yes, the 18 UR eliminations are slightly different, depending on the order, but the end result is the same.

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5166
Location: Rochester, NY, USA

PostPosted: Sat Aug 16, 2014 10:51 pm    Post subject: Reply with quote

Quote:
Marty, this chain is proposed as an alternative to yours, after the UR is played.


Maybe I'm having a day full of senior moments, but after the UR is played (at least the way I played it) the puzzle is solved and there's no need for a chain or anything else after the UR.
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keith



Joined: 19 Sep 2005
Posts: 3179
Location: near Detroit, Michigan, USA

PostPosted: Sun Aug 17, 2014 2:09 am    Post subject: Reply with quote

Marty R. wrote:
Code:

+-----------------+-----------------+---------------+
| 1    23579 4    | 3679  35679 36  | 8    259  67  |
| 2569 8     2679 | 4     15679 16  | 2679 1259 3   |
| 569  3579  679  | 13679 8     2   | 679  159  4   |
+-----------------+-----------------+---------------+
| 268  24    268  | 13    13    5   | 246  7    9   |
| 2569 2459  3    | 269   2469  7   | 1    28   68  |
| 7    1     269  | 8     2469  46  | 246  3    5   |
+-----------------+-----------------+---------------+
| 4    6     128  | 5     23    38  | 79   89   178 |
| 3    27    18   | 267   267   9   | 5    4    18  |
| 89   79    5    | 17    147   148 | 3    6    2   |
+-----------------+-----------------+---------------+

Play this puzzle online at the Daily Sudoku site

On puzzles like this I populate the grid via Draw/Play which greatly minimizes the chance of a mechanical error.

Type 3 UR (18), r78,c39

2r7c3=7r7c9-(7=6)r1c9-(6=8)r5c9-(8=2)r5c8-r5c45=r6c5=>r7c5<>2


Maybe I'm having a senior moment, but I think Marty published a solution with a UR and then a chain?

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5166
Location: Rochester, NY, USA

PostPosted: Sun Aug 17, 2014 3:53 am    Post subject: Reply with quote

keith wrote:
Marty R. wrote:
Code:

+-----------------+-----------------+---------------+
| 1    23579 4    | 3679  35679 36  | 8    259  67  |
| 2569 8     2679 | 4     15679 16  | 2679 1259 3   |
| 569  3579  679  | 13679 8     2   | 679  159  4   |
+-----------------+-----------------+---------------+
| 268  24    268  | 13    13    5   | 246  7    9   |
| 2569 2459  3    | 269   2469  7   | 1    28   68  |
| 7    1     269  | 8     2469  46  | 246  3    5   |
+-----------------+-----------------+---------------+
| 4    6     128  | 5     23    38  | 79   89   178 |
| 3    27    18   | 267   267   9   | 5    4    18  |
| 89   79    5    | 17    147   148 | 3    6    2   |
+-----------------+-----------------+---------------+

Play this puzzle online at the Daily Sudoku site

On puzzles like this I populate the grid via Draw/Play which greatly minimizes the chance of a mechanical error.

Type 3 UR (18), r78,c39

2r7c3=7r7c9-(7=6)r1c9-(6=8)r5c9-(8=2)r5c8-r5c45=r6c5=>r7c5<>2


Maybe I'm having a senior moment, but I think Marty published a solution with a UR and then a chain?

Keith


Keith,

We haven't been on the same wave length. My solution was a one-step chain. But the UR was the basis for the chain. It was a Type 3 and to kill the DP either r7c3=2 or r7c9=7. Thus the UR gave me the premise for the chain. I did nothing with the UR other than to use the extra candidates as the potential pincers, the equivalent of (2=7) as the starting point of the chain.

Hope that clears things up.

Marty
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dongrave



Joined: 06 Mar 2014
Posts: 55

PostPosted: Sun Aug 17, 2014 2:45 pm    Post subject: Reply with quote

Hi Marty, NOW I see what you're talking about! Just like Keith, I thought that your solution consisted of two steps (the UR followed by the chain). It wasn't until I saw your last post that I realized that you were performing the chain without first executing the UR. I probably should have realized it since your solution began '2r7c3=7r7c9...' instead of '(2=1)r7c3-(1=7)r7c9...' but I'm still learning Eureka notation. To avoid this kind of confusion, is it possible to include that fact that you're applying the UR during the steps of the chain within the Eureka expression? For instance, something like '2r7c3=(7r7c9=UR:18r78c39)-(7=6)r1c9...' or is that not the standard convention? Thanks, Don.
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Marty R.



Joined: 12 Feb 2006
Posts: 5166
Location: Rochester, NY, USA

PostPosted: Sun Aug 17, 2014 3:29 pm    Post subject: Reply with quote

Don, some people do embed UR information within the notation. I'm not crazy about it. I'm sorry that it was confusing. I wonder if it would've been clearer if I did it all on one line, like below.

Type 3 UR (18), r78,c39: 2r7c3=7r7c9-(7=6)r1c9-(6=8)r5c9-(8=2)r5c8-r5c45=r6c5=>r7c5<>2
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keith



Joined: 19 Sep 2005
Posts: 3179
Location: near Detroit, Michigan, USA

PostPosted: Sun Aug 17, 2014 4:36 pm    Post subject: Reply with quote

Marty,

I saw the (your) UR as a Type 4 that then opens up the chain as a second step.

Eureka is not my strong point, I just follow the cells and not the link switches.

Maybe the Gods of Eureka can figure out a neater way to denote the pseudocells that can arise in URs (and other "almost" patterns).

Keith
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Clement



Joined: 24 Apr 2006
Posts: 684
Location: Dar es Salaam Tanzania

PostPosted: Sun Aug 17, 2014 11:08 pm    Post subject: Free Press August 15, 2014 Reply with quote

Code:

+----------------+-----------------+---------------+
| 1    2359 4    | 3679  35679 h36  | 8    259  67  |
| 2569 8    2679 | 4     15679 16  | 2679 1259 3   |
| 569  3579 679  | 13679 8     2   | 679  159  4   |
+----------------+-----------------+---------------+
| 268  d24   268  | 13    13    5   | e246  7    9   |
| 2569 2459 3    | 269   2469  7   | 1    28   68  |
| 7    1    269  | 8     2469  g46  | f246  3    5   |
+----------------+-----------------+---------------+
| 4    6    b128  | 5     a23    8-3  | 79   89   178 |
| 3    c27   18   | 267   267   9   | 5    4    18  |
| 89   79   5    | 17    147   148 | 3    6    2   |
+----------------+-----------------+---------------+
(3=2)r7c5-r7c3=r8c2-(2=4)r4c2-r4c7=r6c7-(4=6)r6c6-(6=3)r1c6 => -3r7c6; stte.
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