March 22, 2014

Post puzzles for others to solve here.

March 22, 2014

Postby ArkieTech » Sat Mar 22, 2014 11:02 pm

Missed this one somehow??? :oops:

Code: Select all
 *-----------*
 |2..|6..|.8.|
 |...|4..|7.5|
 |..4|.87|.1.|
 |---+---+---|
 |..7|...|..6|
 |.6.|248|.7.|
 |8..|...|5..|
 |---+---+---|
 |.8.|13.|6..|
 |5.6|..4|...|
 |.1.|..2|..7|
 *-----------*
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Re: March 22, 2014

Postby SteveG48 » Sun Mar 23, 2014 12:49 am

Code: Select all
 *-----------------------------------------------------------*
 | 2     7    e13    | 6     5     139   | 4     8    f39    |
 | 139   39    8     | 4     2     13    | 7     6     5     |
 | 6     5     4     |h39    8     7     | 2     1    g39    |
 *-------------------+-------------------+-------------------|
 | 139   24    7     | 5     19    39    | 8     24    6     |
 | 39    6     5     | 2     4     8     | 39    7     1     |
 | 8     2349 b123   |i379   179   6     | 5    a9-3   24    |
 *-------------------+-------------------+-------------------|
 | 7     8     29    | 1     3     5     | 6     249   24    |
 | 5    c23    6     | 79    79    4     | 1    b23    8     |
 | 4     1    d39    | 8     6     2     | 39    5     7     |
 *-----------------------------------------------------------*


(3)r6c8 - r6c3|r8c8 = r8c2 - r9c3 = r1c3 -r1c9 = r3c9 - r3c4 = r6c4 => -3 r6c8 ; stte
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Re: March 22, 2014

Postby pjb » Sun Mar 23, 2014 2:30 am

Code: Select all
 2      7      13     | 6      5      139    | 4      8      39     
 139    39     8      | 4      2      13     | 7      6      5     
 6      5      4      | 39     8      7      | 2      1      39     
 ---------------------+----------------------+---------------------
 139   *24     7      | 5      19     39     | 8     *24     6     
#39     6      5      | 2      4      8      |#39     7      1     
 8      2349   123    | 379    179    6      | 5      39     24     
 ---------------------+----------------------+---------------------
 7      8      29     | 1      3      5      | 6      249    24     
 5     * 23     6      | 79     79     4      | 1     *23     8     
 4      1     #39     | 8      6      2      |#39     5      7     

Rather than a rather complicated chain,
X-Wing of 2s at r48c28
Sashimi X-Wing (skyscraper) of 3s at r5c17, r9c37
Sashimi swordfish of 3s at r268c2, r36c4, r68c8; stte

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Re: March 22, 2014

Postby JC Van Hay » Sun Mar 23, 2014 6:58 am

Code: Select all
+------------------+----------------+----------------+
| 2      7     13  | 6    5    139  | 4     8     39 |
| 19(3)  9(3)  8   | 4    2    1(3) | 7     6     5  |
| 6      5     4   | 39   8    7    | 2     1     39 |
+------------------+----------------+----------------+
| 19(3)  24    7   | 5    19   9(3) | 8     24    6  |
| 9(3)   6     5   | 2    4    8    | 9(3)  7     1  |
| 8      2349  123 | 379  179  6    | 5     9-3   24 |
+------------------+----------------+----------------+
| 7      8     29  | 1    3    5    | 6     249   24 |
| 5      2(3)  6   | 79   79   4    | 1     2(3)  8  |
| 4      1     39  | 8    6    2    | 9-3   5     7  |
+------------------+----------------+----------------+
SashimiJellyfish(3R2458) : [r8c8=r8c2-r2c2=XWing(r24c16)-r5c1=r5c7]-[(3=9)r6c8 AND (3=9)r9c7]; ste
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Re: March 22, 2014

Postby ArkieTech » Sun Mar 23, 2014 9:46 am

Code: Select all
 *-----------------------------------------------------------*
 | 2     7    *13    | 6     5     139   | 4     8    *39    |
 | 139   39    8     | 4     2     13    | 7     6     5     |
 | 6     5     4     |*39    8     7     | 2     1    *39    |
 |-------------------+-------------------+-------------------|
 | 139   24    7     | 5     19    39    | 8     24    6     |
 | 39    6     5     | 2     4     8     | 39    7     1     |
 | 8     2349 *123   |*379   179   6     | 5    *39    24    |
 |-------------------+-------------------+-------------------|
 | 7     8     29    | 1     3     5     | 6     249   24    |
 | 5     2-3   6     | 79    79    4     | 1    *23    8     |
 | 4     1    f39    | 8     6     2     | 39    5     7     |
 *-----------------------------------------------------------*
Finned Jellyfish
3r1368c3489=3r9c3 => -3r8c2
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Re: March 22, 2014

Postby Leren » Sun Mar 23, 2014 10:53 am

Code: Select all
*--------------------------------------------------------------*
| 2     7     13     | 6     5     139    | 4     8     39     |
|*139  *39    8      | 4     2    *13     | 7     6     5      |
| 6     5     4      | 39    8     7      | 2     1     39     |
|--------------------+--------------------+--------------------|
|*139   24    7      | 5     19   *39     | 8     24    6      |
|*39    6     5      | 2     4     8      |*39    7     1      |
| 8     2349  123    | 379   179   6      | 5     39    24     |
|--------------------+--------------------+--------------------|
| 7     8     29     | 1     3     5      | 6     249   24     |
| 5    *23    6      | 79    79    4      | 1     23    8      |
| 4     1    f39     | 8     6     2      | 9-3   5     7      |
*--------------------------------------------------------------*

Finned Franken Jellyfish r245b7 / c1267 fin r9c3 => - 3 r9c7; stte

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Re: March 22, 2014

Postby tlanglet » Sun Mar 23, 2014 1:04 pm

Code: Select all
 *-----------------------------------------------------------*
 | 2     7     13    | 6     5     139   | 4     8     39    |
 | 139   39    8     | 4     2     13    | 7     6     5     |
 | 6     5     4     | 39    8     7     | 2     1     39    |
 |-------------------+-------------------+-------------------|
 | 139   24    7     | 5     19    39    | 8     24    6     |
 | 39    6     5     | 2     4     8     | 39    7     1     |
 | 8    *39=24 12-3  | 79-3  179   6     | 5    *39    24    |
 |-------------------+-------------------+-------------------|
 | 7     8     29    | 1     3     5     | 6     249   24    |
 | 5     23    6     | 79    79    4     | 1     23    8     |
 | 4     1     39    | 8     6     2     | 39    5     7     |
 *-----------------------------------------------------------*

Another "out of the ordinary" solution is an

ANP(39=24)r6c92-als(24=3)r468-r8c8=3r6c8 => r6c34<>3

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Postby blue » Sun Mar 23, 2014 2:34 pm

Code: Select all
+------------------+-----------------+-----------------+
| 2    7     19(3) | 6      5    139 | 4    8     9(3) |
| 139  39    8     | 4      2    13  | 7    6     5    |
| 6    5     4     | 9(3)   8    7   | 2    1     9(3) |
+------------------+-----------------+-----------------+
| 139  24    7     | 5      19   39  | 8    24    6    |
| 39   6     5     | 2      4    8   | 39   7     1    |
| 8    2349  12(3) | 79(3)  179  6   | 5    9(3)  24   |
+------------------+-----------------+-----------------+
| 7    8     29    | 1      3    5   | 6    249   24   |
| 5    2-3   6     | 79     79   4   | 1    2(3)  8    |
| 4    1     9(3)  | 8      6    2   | 9-3  5     7    |
+------------------+-----------------+-----------------+

(3) r9c3 = (Swordfish: c349\r136) - r6c8 = r8c8 => r8c2<>3, r9c7<>3; stte
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Re: March 22, 2014

Postby daj95376 » Sun Mar 23, 2014 6:21 pm

SteveG48 wrote:
Code: Select all
 *-----------------------------------------------------------*
 | 2     7    e13    | 6     5     139   | 4     8    f39    |
 | 139   39    8     | 4     2     13    | 7     6     5     |
 | 6     5     4     |h39    8     7     | 2     1    g39    |
 *-------------------+-------------------+-------------------|
 | 139   24    7     | 5     19    39    | 8     24    6     |
 | 39    6     5     | 2     4     8     | 39    7     1     |
 | 8     2349 b123   |i379   179   6     | 5    a9-3   24    |
 *-------------------+-------------------+-------------------|
 | 7     8     29    | 1     3     5     | 6     249   24    |
 | 5    c23    6     | 79    79    4     | 1    b23    8     |
 | 4     1    d39    | 8     6     2     | 39    5     7     |
 *-----------------------------------------------------------*


(3)r6c8 - r6c3|r8c8 = r8c2 - r9c3 = r1c3 -r1c9 = r3c9 - r3c4 = r6c4 => -3 r6c8 ; stte

Steve, I know that you prefer to start with a weak link and use network logic. That's perfectly okay. However, the hairs on my neck stood up when you also chose to selectively ignore another elimination as well. If you're going to use "(3)r6c8 - r6c3|r8c8", then you selectively ignored -r6c4 -- which would prevent your final conclusion of "= r6c4". What I see:

Code: Select all
(3)r6c8 - r6c34,r8c8 = r8c2 - r9c3 = r1c3 -r1c9 = r3c9 - r36c4; contradiction [c3]  =>  -3 r6c8 ; stte
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Re: March 22, 2014

Postby daj95376 » Sun Mar 23, 2014 6:45 pm

_

There are many Jellyfish that perform a single elimination that cracks this puzzle. Siamese combinations also exist:

Code: Select all
 +--------------------------------------------------------------+
 |  2     7    *13    |  6     5     139   |  4     8    *39    |
 |  139   39    8     |  4     2     13    |  7     6     5     |
 |  6     5     4     | *39    8     7     |  2     1    *39    |
 |--------------------+--------------------+--------------------|
 |  139   24    7     |  5     19    39    |  8     24    6     |
 |  39    6     5     |  2     4     8     |  39    7     1     |
 |  8     2349 *123   | *379   179   6     |  5    *39    24    |
 |--------------------+--------------------+--------------------|
 |  7     8     29    |  1     3     5     |  6     249   24    |
 |  5     23    6     |  79    79    4     |  1    *23    8     |
 |  4     1    *39    |  8     6     2     |  39    5     7     |
 +--------------------------------------------------------------+
 # 39 eliminations remain

 Siamese Sashimi Jellyfish c3489\r136+8|9  =>  -3 r8c2|r9c7

Since others chose to include single-value chains/networks, I re-examined the above solution and noticed that r6c3 was the only (*) cell that saw more than one other (*) cell in a row and column:

Code: Select all
 3r9c3 = r1c3 - r1c9 = r3c9 - r3c4 = r6c4 - r6c8 = 3r8c8  =>  -3 r8c2,r9c7
          ||                             /
       = r6c3                           /
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Re: March 22, 2014

Postby Leren » Sun Mar 23, 2014 8:33 pm

Code: Select all
*---------------------------------------------------------------*
| 2     7     h1-3    | 6     5     139    | 4     8     39     |
| 139   39     8      | 4     2     13     | 7     6     5      |
| 6     5      4      | 39    8     7      | 2     1     39     |
|---------------------+--------------------+--------------------|
| 139   24     7      | 5     19    39     | 8     24    6      |
| 39    6      5      | 2     4     8      | 39    7     1      |
| 8     2349 eg12-3   |e79+3 f79+1  6      | 5    d39    24     |
|---------------------+--------------------+--------------------|
| 7     8      29     | 1     3     5      | 6     249   24     |
| 5    b23     6      | 79    79    4      | 1    c23    8      |
| 4     1     a39     | 8     6     2      | 39    5     7      |
*---------------------------------------------------------------*

Potential UR (79) r68c45.

(3) r9c3 = r8c2 - r8c8 = r6c8 - (3) r6c34 = UR = (1) r6c5 - (13) r6c3 = (1-3) r1c3 => - 3 r16c3; stte

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Re: March 22, 2014

Postby SteveG48 » Sun Mar 23, 2014 8:57 pm

daj95376 wrote:Steve, I know that you prefer to start with a weak link and use network logic. That's perfectly okay. However, the hairs on my neck stood up when you also chose to selectively ignore another elimination as well. If you're going to use "(3)r6c8 - r6c3|r8c8", then you selectively ignored -r6c4 -- which would prevent your final conclusion of "= r6c4". What I see:

Code: Select all
(3)r6c8 - r6c34,r8c8 = r8c2 - r9c3 = r1c3 -r1c9 = r3c9 - r36c4; contradiction [c3]  =>  -3 r6c8 ; stte


Thanks, Danny. Actually, I prefer not to use network logic if I see a solution that doesn't need it, and I'm trying to vary my solutions so that I'm not always starting with a weak link. Your criticism of the selective ignoring of an elimination makes sense, and I like your alternative of accepting a contradiction not directly involving the first link in the chain. I've used that on occasion, but sensed that people don't care for it too much.
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Re: March 22, 2014

Postby Marty R. » Mon Mar 24, 2014 1:14 am

Code: Select all
+--------------+-------------+-----------+
| 2   7    13  | 6   5   139 | 4  8   39 |
| 139 39   8   | 4   2   13  | 7  6   5  |
| 6   5    4   | 39  8   7   | 2  1   39 |
+--------------+-------------+-----------+
| 139 24   7   | 5   19  39  | 8  24  6  |
| 39  6    5   | 2   4   8   | 39 7   1  |
| 8   2349 123 | 379 179 6   | 5  39  24 |
+--------------+-------------+-----------+
| 7   8    29  | 1   3   5   | 6  249 24 |
| 5   23   6   | 79  79  4   | 1  23  8  |
| 4   1    39  | 8   6   2   | 39 5   7  |
+--------------+-------------+-----------+

Play this puzzle online at the Daily Sudoku site

Couldn't find the one-stepper.

Coloring: 3r2c12=r1c3-r9c3=r9c7-r5c7=r6c8-r6c4=3r4c6=>r2c6<>3
BUG+2 finishes it off.
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Re: March 22, 2014

Postby DonM » Mon Mar 24, 2014 2:39 am

SteveG48 wrote:
daj95376 wrote:Steve, I know that you prefer to start with a weak link and use network logic. That's perfectly okay. However, the hairs on my neck stood up when you also chose to selectively ignore another elimination as well. If you're going to use "(3)r6c8 - r6c3|r8c8", then you selectively ignored -r6c4 -- which would prevent your final conclusion of "= r6c4". What I see:

Code: Select all
(3)r6c8 - r6c34,r8c8 = r8c2 - r9c3 = r1c3 -r1c9 = r3c9 - r36c4; contradiction [c3]  =>  -3 r6c8 ; stte


...and I'm trying to vary my solutions so that I'm not always starting with a weak link.


Why do it at all?

From the man who put AICs on the map:

Alternating Inference Chains
by Myth Jellies » Sat Apr 15, 2006 7:23 am

Alternating Inference Chains

Definitions
Alternating Inference Chain (AIC) is a chain which starts with an endpoint candidate which has a strong inference on the next candidate, which has a weak inference on the next candidate, which has a strong inference on the next candidate, and so on alternating weak and strong inferences until it ends with a strong inference on the final candidate at the other endpoint. The nodes of an AIC are really just the candidate premises themselves.

From: http://forum.enjoysudoku.com/alternating-inference-chains-t3865.html
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Re: March 22, 2014

Postby SteveG48 » Tue Mar 25, 2014 1:41 am

DonM wrote:
SteveG48 wrote:
daj95376 wrote:Steve, I know that you prefer to start with a weak link and use network logic. That's perfectly okay. However, the hairs on my neck stood up when you also chose to selectively ignore another elimination as well. If you're going to use "(3)r6c8 - r6c3|r8c8", then you selectively ignored -r6c4 -- which would prevent your final conclusion of "= r6c4". What I see:

Code: Select all
(3)r6c8 - r6c34,r8c8 = r8c2 - r9c3 = r1c3 -r1c9 = r3c9 - r36c4; contradiction [c3]  =>  -3 r6c8 ; stte


...and I'm trying to vary my solutions so that I'm not always starting with a weak link.


Why do it at all?


Because sometimes it's useful for arriving at a solution.

From the man who put AICs on the map:

Alternating Inference Chains
by Myth Jellies » Sat Apr 15, 2006 7:23 am

Alternating Inference Chains

Definitions
Alternating Inference Chain (AIC) is a chain which starts with an endpoint candidate which has a strong inference on the next candidate, which has a weak inference on the next candidate, which has a strong inference on the next candidate, and so on alternating weak and strong inferences until it ends with a strong inference on the final candidate at the other endpoint. The nodes of an AIC are really just the candidate premises themselves.

From: http://forum.enjoysudoku.com/alternating-inference-chains-t3865.html


Which seems to mean that a chain that starts with a weak link isn't properly called an AIC. Does that make it less useful? I've also seen solutions posted that end with a weak link to get a useful elimination. Should we also avoid that?
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