Fun puzzle. So many methods to solve. No CHAINS required.

Post puzzles for others to solve here.

Postby wapati » Wed Oct 18, 2006 4:45 pm

If you like finny fish, you'll enjoy this one.:)

Code: Select all
2 . . | . 4 . | . 8 .
. . 4 | . . . | 9 . 1
. 1 . | . . 9 | 2 3 .
---------------------
. 3 . | . . 6 | 5 . .
. . 7 | 2 . . | . . 6
6 . . | . 5 . | . . .
---------------------
. . 1 | . 3 . | . 9 .
. 7 . | . . 4 | 1 . .
4 . . | 6 . . | . . 8
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Postby Carcul » Wed Oct 18, 2006 9:58 pm

Wapati wrote:If you like finny fish, you'll enjoy this one.


Code: Select all
 *--------------------------------------------------------------------*
 | 2       59      359   | 1357    4       1357 | 6       8       57  |
 | 3578    58      4     | 3578    6       2    | 9       57      1   |
 | 578     1       6     | 578     78      9    | 2       3       4   |
 |-----------------------+----------------------+---------------------|
 | 189     3       289   | 14789   1789    6    | 5       124     79  |
 | 1589    4589    7     | 2       189     138  | 38      14      6   |
 | 6       2489    289   | 134789  5       1378 | 378     124     379 |
 |-----------------------+----------------------+---------------------|
 | 58      6       1     | 578     3       578  | 4       9       2   |
 | 3589    7       23589 | 589     289     4    | 1       6       35  |
 | 4       259     2359  | 6       129     15   | 37      57      8   |
 *--------------------------------------------------------------------*

[r8c4](-9-[r46c4])-9-[r8c1]=9=[X-Wing: r45c15]-9-[r4c9](-7-[r6c9]=7=
=[r7c6]-7-[r6c6])-7-[r6c7]=7=[r9c7]-7-[r9c8]-5-[r9c6]-1-[r56c6],

and the cells r56c67 are all and only populated by “3,8”. So, r8c4 cannot be “9” and the puzzle is solved.

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Postby RW » Wed Oct 18, 2006 10:40 pm

carcul wrote:[r8c4](-9-[r46c4])-9-[r8c1]=9=[X-Wing: r45c15]-9-[r4c9](-7-[r6c9]=7=
=[r7c6]-7-[r6c6])-7-[r6c7]=7=[r9c7]-7-[r9c8]-5-[r9c6]-1-[r56c6]

Once again there's too much sand for my truck... "(-7-[r6c9]=7= =[r7c6]-7-...":?::?:

You started such a nice chain there, why not keep it simple:

[r8c4](-9-[r46c4])-9-[r8c1]=9=[X-Wing: r45c15]-9-[r4c9](-7-[r1c9])-7-[r4c5]=7=[r3c5]-7-[r1c46]

=> r8c4<>9

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Postby wapati » Thu Oct 19, 2006 4:37 am

This one needs at least 4.

Chain gang..I dunno.:)

Code: Select all
. . . | . 7 . | . 1 .
. 7 . | 1 . . | . 5 6
3 . . | . . . | 8 . .
---------------------
. . . | . 4 . | . . .
. 3 . | 6 9 1 | . . 7
6 . 1 | . 3 . | . 4 .
---------------------
. 2 9 | 3 . . | . . .
. . 7 | . 8 . | . 2 .
1 . . | 2 . . | 4 . .
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Postby wapati » Thu Oct 19, 2006 5:26 am

So way nasty for me.

This is about my limit, nice one.

Code: Select all
. 9 2 | . . . | 7 8 .
1 . . | . 7 . | . . 4
7 . . | 9 . 3 | . . 6
---------------------
. . 9 | 7 . 5 | 3 . .
. 1 . | . . . | . 7 .
. . 5 | 8 . 4 | 6 . .
---------------------
9 . . | 3 . 7 | . . 1
2 . . | . 8 . | . . 7
. 3 7 | . . . | 8 6 .


I have a question, I am sure here is wrong. <sigh>

I was wondering what the pattern is, for "good puzzles" when you take the givens and add a correct not given and see whether it is now an "easy".

I didn't say that well.

I wonder whether most "good" puzzles have any, more than 1, lots of squares, that if filled in render the puzzle easy.

I'd like to know if there are more than one squares that may be critical.
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Postby wapati » Thu Oct 19, 2006 5:53 am

WOW! This one is past my limit.

I sort-of know Sashimi X.

Hrrmmm. Here is a borrible. Happy Dancing!

Code: Select all
. . . | . . . | . . .
. 8 6 | . 1 . | 5 2 .
1 . 7 | . . . | 3 . 8
---------------------
. . 2 | 5 . 7 | 1 . .
. 3 1 | . 6 . | 2 5 .
. . . | . 9 . | . . .
---------------------
. . 4 | . . . | 6 . .
. . 3 | . 8 . | 9 . .
7 . . | 6 . 1 | . . 2
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Postby ravel » Thu Oct 19, 2006 8:43 am

wapati wrote:I have a question, I am sure here is wrong. <sigh>

I was wondering what the pattern is, for "good puzzles" when you take the givens and add a correct not given and see whether it is now an "easy".
You are talking about "backdoor" cells. It depends on what you define as "easy", what a backdoor is. With the basics i have implemented (box/line, tuples, x-wing, UR1) your puzzle has 15.
When you allow the Simple Sudoku techniques (box/line, tuples, x-,xy-wing, swordfish, multicoloring) only one puzzle is known, that does not have a single backdoor (nr 210 in my old list):

33: Ocean #10/M21/D21 (ER 9.8, gsfr 99650, suexr 977, RMS 8)
.....1..2.3..4..5.6..2.......5.....3.7..8..4.2.....9..9....4.......5..7...41..6..
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Postby RW » Thu Oct 19, 2006 9:26 am

wapati wrote:This one needs at least 4.

Chain gang..I dunno.:)
Code: Select all
. . . | . 7 . | . 1 .
. 7 . | 1 . . | . 5 6
3 . . | . . . | 8 . .
---------------------
. . . | . 4 . | . . .
. 3 . | 6 9 1 | . . 7
6 . 1 | . 3 . | . 4 .
---------------------
. 2 9 | 3 . . | . . .
. . 7 | . 8 . | . 2 .
1 . . | 2 . . | 4 . .

4 of what?
Code: Select all
 *-----------------------------------------------------------------------------*
 | 24589   458     24568   | 4589    7       345689  | 239     1       249     |
 | 489     7       48      | 1       2       3489    | 39      5       6       |
 | 3       1       2456    | 459     56      4569    | 8       7       249     |
 |-------------------------+-------------------------+-------------------------|
 | 7       9       258     | 58      4       258     | 6       3       1       |
 | 245     3       245     | 6       9       1       | 25      8       7       |
 | 6       58      1       | 7       3       258     | 259     4       29      |
 |-------------------------+-------------------------+-------------------------|
 | 458     2       9       | 3       1       45      | 7       6       58      |
 | 45      456     7       | 459     8       4569    | 1       2       3       |
 | 1       568     3       | 2       56      7       | 4       9       58      |
 *-----------------------------------------------------------------------------*

[r4c3](-8-[r6c2]-5-[r1c2])-8-[r2c3]-4-[r1c2]-8-[r1c4]=8=[r4c4]-8-[r4c3]

=> r4c3<>8

Sorry if I spoiled your fun carcul...

RW
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Postby wapati » Thu Oct 19, 2006 4:22 pm

RW wrote:4 of what?
[RW


I would need x, xy, xyz, swordish and ER/Turbot to complete it.

Your way looks shorter.:D
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Postby RW » Thu Oct 19, 2006 4:29 pm

wapati wrote:I would need x, xy, xyz, swordish and ER/Turbot to complete it.


No, you wouldn't. ER + XY-wing is enough. You shouldn't trust a computer program to tell you what is required, it tells you what is required if you do the techniques in a specific order.

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Postby Carcul » Thu Oct 19, 2006 9:20 pm

Wapati wrote:This is about my limit, nice one.


Code: Select all
 *-----------------------------------------------------*
 | 456   9     2   | 1456  456   16  | 7     8     3   |
 | 1     56    3   | 256   7     8   | 259   259   4   |
 | 7     458   48  | 9     245   3   | 1     25    6   |
 |-----------------+-----------------+-----------------|
 | 46    2     9   | 7     16    5   | 3     14    8   |
 | 8     1     46  | 26    3     269 | 2459  7     259 |
 | 3     7     5   | 8     129   4   | 6     129   29  |
 |-----------------+-----------------+-----------------|
 | 9     4568  468 | 3     2456  7   | 245   245   1   |
 | 2     456   1   | 456   8     69  | 459   3     7   |
 | 45    3     7   | 1245  2459  129 | 8     6     259 |
 *-----------------------------------------------------*

We have r5c7=9 or r9c9=5. But:

[r5c7]=9|5=[r9c9]-5-[r5c9]=5=[r5c7],

which implies r5c7<>2,4 and the puzzle is solved (using later a trivial ATILA step).

Carcul
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Postby Carcul » Thu Oct 19, 2006 9:40 pm

Wapati wrote:WOW! This one is past my limit.(...) Hrrmmm. Here is a borrible. Happy Dancing!


Code: Select all
 *---------------------------------------------------------------------*
 | 2345    2459    59  | 3489    245     345689 | 7       1469    1469 |
 | 34      8       6   | 7       1       349    | 5       2       49   |
 | 1       2459    7   | 49      245     4569   | 3       469     8    |
 |---------------------+------------------------+----------------------|
 | 468     46      2   | 5       3       7      | 1       4689    469  |
 | 9       3       1   | 48      6       48     | 2       5       7    |
 | 456     7       58  | 1       9       2      | 48      46      3    |
 |---------------------+------------------------+----------------------|
 | 258     125     4   | 39      7       39     | 6       18      15   |
 | 56      156     3   | 2       8       45     | 9       7       145  |
 | 7       59      589 | 6       45      1      | 48      3       2    |
 *---------------------------------------------------------------------*

[r6c3]-8-[r9c3]=8=[r7c1]=2=[r7c2]-2-[r1c2]-4-[r4c2]-6-[r24c9]
-4-[r8c9]=4=[r9c7]=8=[r6c7]-8-[r6c3],

and so r6c3<>8 solving the puzzle.

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Postby wapati » Fri Oct 20, 2006 5:12 am

RW wrote:
wapati wrote:I would need x, xy, xyz, swordish and ER/Turbot to complete it.


No, you wouldn't. ER + XY-wing is enough. You shouldn't trust a computer program to tell you what is required, it tells you what is required if you do the techniques in a specific order.

RW


Sheesh, next you will tell me that "windows" isn't safe on the Internet.:?:
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Postby wapati » Fri Oct 20, 2006 5:18 am

This is hard for me, many methods required.

Code: Select all
. . 6 | . 2 . | . . 4
5 9 . | . . . | . . .
. . 4 | . . 9 | 8 . .
---------------------
. . . | . 7 4 | 1 . .
. . 8 | 6 . 1 | . . 3
4 . . | . 3 . | . . .
---------------------
. . . | . 8 . | 3 . 2
8 5 . | . . . | . 6 .
. 7 . | 2 . . | . 9 .
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Postby RW » Fri Oct 20, 2006 6:03 am

wapati wrote:Sheesh, next you will tell me that "windows" isn't safe on the Internet.:?:

Well, if you write two post that claims that it is, then maybe I would...

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