Vanhegan Fiendish February 8, 2013

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Vanhegan Fiendish February 8, 2013

Postby ArkieTech » Tue Feb 12, 2013 8:04 am

Code: Select all
 *-----------*
 |.23|.97|5..|
 |...|...|9.8|
 |51.|6..|..7|
 |---+---+---|
 |1..|.2.|7..|
 |7..|9.3|..5|
 |..5|.7.|..2|
 |---+---+---|
 |9..|..2|.74|
 |2.6|...|...|
 |..7|81.|25.|
 *-----------*


Play/Print this puzzle online
dan
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Re: Vanhegan Fiendish February 8, 2013

Postby Leren » Tue Feb 12, 2013 9:02 am

Code: Select all
*--------------------------------------------------------------------------------*
| 8       2       3        |a14      9       7        | 5       146     16       |
| 6       7       4        | 2       35     b15       | 9       13      8        |
| 5       1       9        | 6       348    d8-4      | 34      2       7        |
|--------------------------+--------------------------+--------------------------|
| 1       3469    8        | 5       2       46       | 7       3469    369      |
| 7       46      2        | 9       468     3        | 1468    1468    5        |
| 34      3469    5        | 14      7      c1468     | 3468    34689   2        |
|--------------------------+--------------------------+--------------------------|
| 9       58      1        | 3       56      2        | 68      7       4        |
| 2       58      6        | 7       45      459      | 138     1389    139      |
| 34      34      7        | 8       1       69       | 2       5       69       |
*--------------------------------------------------------------------------------*


h-wing: (4=1) r1c4 - r2c6 = (1-8) r6c6 = r3c6 => r3c6 <> 4;

Code: Select all
*--------------------------------------------------------------------------------*
| 8       2       3        | 4       9       7        | 5       6       1        |
| 6       7       4        | 2       5       1        | 9       3       8        |
| 5       1       9        | 6       3       8        | 4       2       7        |
|--------------------------+--------------------------+--------------------------|
| 1      A4-3-6   8        | 5       2       46       | 7       49      39       |
| 7       46      2        | 9       8       3        | 16      14      5        |
| 34      9       5        | 1       7       46       | 36      8       2        |
|--------------------------+--------------------------+--------------------------|
| 9       5       1        | 3       6       2        | 8       7       4        |
| 2       8       6        | 7       4       5        | 13      19      39       |
| 34      34      7        | 8       1       9        | 2       5       6        |
*--------------------------------------------------------------------------------*


BUG+1 => r4c2 <> 3,6; stte

Leren
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Re: Vanhegan Fiendish February 8, 2013

Postby pjb » Tue Feb 12, 2013 10:31 am

Also no single step solution. But a different approach to Leren's first elimination:
(4=1) r1c4 - (1=4)r2489c6, => r3c6 <> 4

An alternate 2nd step
(3=4) r6c1 - (4=6) r5c2 - (6=1)r5c7 - (1=3) r8c7 => r6c7 <> 3; stte

Phil
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Re: Vanhegan Fiendish February 8, 2013

Postby aran » Tue Feb 12, 2013 1:01 pm

Code: Select all
*--------------------------------------------------------------------*
 | 8      2      3      | 14     9      7      | 5      146    16     |
 | 6      7      4      | 2      35     15     | 9      13     8      |
 | 5      1      9      | 6      348    48     | 34     2      7      |
 |----------------------+----------------------+----------------------|
 | 1      3469   8      | 5      2      46     | 7      3469   369    |
 | 7      46     2      | 9      468    3      | 1468   1468   5      |
 | 34     3469   5      | 14     7      1468   | 3468   34689  2      |
 |----------------------+----------------------+----------------------|
 | 9      58     1      | 3      56     2      | 68     7      4      |
 | 2      58     6      | 7      45     459    | 138    1389   139    |
 | 34     34     7      | 8      1      69     | 2      5      69     |
 *--------------------------------------------------------------------*

FXW4r16c48 =><4>r6c7
6r6c7=XW6r57c57-6r5c28=4r5c2-(4=3)r6c1-(3=68)r67c7-68r5c7=18r5c78-(8=6)r6c7 : =>r6c7=6 ste
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Re: Vanhegan Fiendish February 8, 2013

Postby eleven » Tue Feb 12, 2013 2:57 pm

aran wrote:68r5c7=18r5c78

Hm, i can't see this link without using 4r5c2 and the x-wing 6 (giving 6r5c5 then) in the earlier part of the chain.
Am i missing something ?
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Re: Vanhegan Fiendish February 8, 2013

Postby daj95376 » Tue Feb 12, 2013 4:26 pm

eleven wrote:
aran wrote:68r5c7=18r5c78

Hm, i can't see this link without using 4r5c2 and the x-wing 6 (giving 6r5c5 then) in the earlier part of the chain.
Am i missing something ?

aran uses selective memory when solving puzzles. I enjoy the challenge of unfolding some of his solutions.

Code: Select all
FXW4r16c48 =><4>r6c7
6r6c7=XW6r57c57-6r5c28=4r5c2-(4=3)r6c1-(3=68)r67c7-68r5c7=18r5c78-(8=6)r6c7 : =>r6c7=6 ste

He remembers both eliminations from the embedded X-Wing and the eliminations from the resulting r5c2=4, but he ignores his initial premise after r6c1=3. This then allows the deduction that tripped you up. Had he remembered his initial premise as well, then he would have been trapped by the contradiction (*) in this grid.

Code: Select all
 *--------------------------------------------------------------*
 |  8     2     3     |  14    9     7     |  5     146   16    |
 |  6     7     4     |  2     35    15    |  9     13    8     |
 |  5     1     9     |  6     348   48    |  34    2     7     |
 |--------------------+--------------------+--------------------|
 |  1     69    8     |  5     2     46    |  7     3469  369   |
 |  7    =4     2     |  9     68    3     | *16   *1     5     |
 | =3     69    5     |  14    7     146   | =8     469   2     |
 |--------------------+--------------------+--------------------|
 |  9     58    1     |  3     56    2     | *6     7     4     |
 |  2     58    6     |  7     45    459   |  13    1389  139   |
 |  4     3     7     |  8     1     69    |  2     5     69    |
 *--------------------------------------------------------------*
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Re: Vanhegan Fiendish February 8, 2013

Postby Marty R. » Tue Feb 12, 2013 6:47 pm

Code: Select all
+-----------+-------------+----------------+
| 8  2    3 | 14 9   7    | 5    146   16  |
| 6  7    4 | 2  35  15   | 9    13    8   |
| 5  1    9 | 6  348 48   | 34   2     7   |
+-----------+-------------+----------------+
| 1  3469 8 | 5  2   46   | 7    3469  369 |
| 7  46   2 | 9  468 3    | 1468 1468  5   |
| 34 3469 5 | 14 7   1468 | 3468 34689 2   |
+-----------+-------------+----------------+
| 9  58   1 | 3  56  2    | 68   7     4   |
| 2  58   6 | 7  45  459  | 138  1389  139 |
| 34 34   7 | 8  1   69   | 2    5     69  |
+-----------+-------------+----------------+

Play this puzzle online at the Daily Sudoku site

XY-Chain: (4=1)r1c4-(1=6)r1c9-(6=9)r9c9-(9=6)r9c6-(6=4)r4c6=>r3c6,r6c4<>4

Code: Select all
+----------+--------+----------+
| 8  2   3 | 4 9 7  | 5  6  1  |
| 6  7   4 | 2 5 1  | 9  3  8  |
| 5  1   9 | 6 3 8  | 4  2  7  |
+----------+--------+----------+
| 1  346 8 | 5 2 46 | 7  49 39 |
| 7  46  2 | 9 8 3  | 16 14 5  |
| 34 9   5 | 1 7 46 | 36 8  2  |
+----------+--------+----------+
| 9  5   1 | 3 6 2  | 8  7  4  |
| 2  8   6 | 7 4 5  | 13 19 39 |
| 34 34  7 | 8 1 9  | 2  5  6  |
+----------+--------+----------+

Play this puzzle online at the Daily Sudoku site

BUG+1, r4c2=4
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Re: Vanhegan Fiendish February 8, 2013

Postby eleven » Tue Feb 12, 2013 6:57 pm

daj95376 wrote:He remembers both eliminations ...

I like this solution, also if it's a damned contradiction (sudopedia oops forcing) chain/net. I guess, not many solvers would find it. Does yours,Danny ?
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Re: Vanhegan Fiendish February 8, 2013

Postby JC Van Hay » Tue Feb 12, 2013 8:09 pm

aran wrote:FXW4r16c48 =><4>r6c7
6r6c7=XW6r57c57-6r5c28=4r5c2-(4=3)r6c1-(3=68)r67c7-68r5c7=18r5c78-(8=6)r6c7 : =>r6c7=6 ste
An interpretation of aran's 2nd step ...
ALS-XZ Rule : (6=43)r5c2.r6c1-(3=68)r67c7 :=> -6r5c7; r5c2=6 to prevent the Broken Wing 6r57c5+6r67c7+6r5c8; ste
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Re: Vanhegan Fiendish February 8, 2013

Postby daj95376 » Tue Feb 12, 2013 8:25 pm

eleven wrote:
daj95376 wrote:He remembers both eliminations ...

I like this solution, also if it's a damned contradiction (sudopedia oops forcing) chain/net. I guess, not many solvers would find it.

Does yours,Danny ?

No. My solver handles some embedded URs and some ALS patterns, but it doesn't handle AHS patterns nor embedded X-Wings. The closest my solver comes is this SIN:

Code: Select all
 after aran's finned X-Wing
 +-----------------------------------------------------------------------+
 |  8      2      3      |  14     9      7      |  5      146    16     |
 |  6      7      4      |  2      35     15     |  9      13     8      |
 |  5      1      9      |  6      348    48     |  34     2      7      |
 |-----------------------+-----------------------+-----------------------|
 |  1      3469   8      |  5      2      46     |  7      3469   369    |
 |  7      46     2      |  9      468    3      |  1468   1468   5      |
 |  34     3469   5      |  14     7      1468   |  368    34689  2      |
 |-----------------------+-----------------------+-----------------------|
 |  9      58     1      |  3      56     2      |  68     7      4      |
 |  2      58     6      |  7      45     459    |  138    1389   139    |
 |  34     34     7      |  8      1      69     |  2      5      69     |
 +-----------------------------------------------------------------------+
 # 61 eliminations remain

 1r8c7  1r1c9  3r2c8  3r6c7  4r6c1  6r5c2  6r7c5  [c7]-6  =>  r8c7<>1
daj95376
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Re: Vanhegan Fiendish February 8, 2013

Postby eleven » Wed Feb 13, 2013 8:30 am

JC Van Hay wrote:
aran wrote:FXW4r16c48 =><4>r6c7
6r6c7=XW6r57c57-6r5c28=4r5c2-(4=3)r6c1-(3=68)r67c7-68r5c7=18r5c78-(8=6)r6c7 : =>r6c7=6 ste
An interpretation of aran's 2nd step ...
ALS-XZ Rule : (6=43)r5c2.r6c1-(3=68)r67c7 :=> -6r5c7; r5c2=6 to prevent the Broken Wing 6r57c5+6r67c7+6r5c8; ste

I don't see that, there are 3 more 6's in box 6 to prevent it.
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Re: Vanhegan Fiendish February 8, 2013

Postby JC Van Hay » Wed Feb 13, 2013 8:40 pm

eleven wrote:
JC Van Hay wrote:
aran wrote:FXW4r16c48 =><4>r6c7
6r6c7=XW6r57c57-6r5c28=4r5c2-(4=3)r6c1-(3=68)r67c7-68r5c7=18r5c78-(8=6)r6c7 : =>r6c7=6 ste
An interpretation of aran's 2nd step ...
ALS-XZ Rule : (6=43)r5c2.r6c1-(3=68)r67c7 :=> -6r5c7; r5c2=6 to prevent the Broken Wing 6r57c5+6r67c7+6r5c8; ste

I don't see that, there are 3 more 6's in box 6 to prevent it.

This time I got myself muddled up ... :(

Anyway, aran's intriguing step can be viewed as a combination of 2 independent steps (-> selective memory) :
a. 6r6c7=XW(6r57c57)-(6=4)r5c2-(4=3)r6c1 :=> -3r6c7
b. (8=6)r7c7-6r7c5=6r5c5-(6=148)r5c278 :=> -8r6c7
or simply
b. (8=6)r7c7-6r7c5=(6-8)r5c5=8r6c6 :=> -8r6c7
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