hard puzzle for solving again! number 3.

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hard puzzle for solving again! number 3.

Postby fredooi » Mon Aug 18, 2008 2:45 am

it's me again......really hard! cant figure out the way. pls help out.
reference: www.MSIGsudoku.com.my on 19 Aug 2008.

Without pencilmarks:
Code: Select all

. . . | 7 . 3 | . 9 2
. . 9 | 1 . 6 | . . .
. . 7 | 4 . 9 | 1 . 3
------+-------+------
. 7 4 | . 1 . | . 2 .
9 . . | 2 6 7 | . . 8
. 2 . | . 4 . | 7 . .
------+-------+------
4 . 1 | 5 . 2 | 9 . .
. . 2 | 8 . . | 5 . .
7 . . | 6 . . | 2 . .





With pencilmarks:
Code: Select all

1568   14568  568  | 7   58   3   | 468  9      2
2358   3458   9    | 1   258  6   | 48   457    457
2568   568    7    | 4   258  9   | 1    56     3
-------------------+--------------+-------------------
3568   7      4    | 39  1    58  | 36   2      569
9      135    35   | 2   6    7   | 43   145    8
13568  2      3568 | 39  4    58  | 7    156    1569
--------------------+--------------+-------------------
4      368    1    | 5   37   2   | 9    3678   67
36     369    2    | 8   379  14  | 5    13467  1467
7      3589   358  | 6   39   14  | 2    1348   14 
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Postby Pat » Mon Aug 18, 2008 5:23 am

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



Code: Select all
1568   14568  568  | 7   58   3   | 468  9      2
2358   3458   9    | 1   258  6   | 48   457    457
2568   568    7    | 4   258  9   | 1    56     3
-------------------+--------------+-----------------
3568   7      4    | 39  1    58  | 36   2      569
9      135    35   | 2   6    7   | 43   145    8
13568  2      3568 | 39  4    58  | 7    156    1569
-------------------+--------------+-----------------
4      368    1    | 5   37   2   | 9    3678   67
36     369    2    | 8   379  14  | 5    13467  1467
7      3589   358  | 6   39   14  | 2    1348   14 




one minor point, you missed the "naked" duo ={1,4} in r9
    however, the puzzle needs more than that -- some forcing chains --

    if the 1 for c2 is in r1
    then the 4 for that row is in c7
    so the 4 for r5 is in c8
    and the 1 for that row is in c2 -- conflict

    in the next step,
    if the 3 for c7 is in r4
    then the 3 for r5 is in c3,
    the 5 for that row is in c8,
    thus r3c8 = 6
    and c7 has no 6 -- conflict.
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Re: hard puzzle for solving again! number 3.

Postby wintder » Mon Aug 18, 2008 8:32 am

fredooi wrote:it's me again......really hard! cant figure out the way. pls help out.


I'd use the skyscraper, also known as sashimi x-wing and also called a turbot, to eliminate some 6s.
Code: Select all
1568   14568 *568  | 7   58   3   |*468  9      2
2358   3458   9    | 1   258  6   | 48   457    457
2568   568    7    | 4   258  9   | 1    56     3
-------------------+--------------+-------------------
358-6  7      4    | 39  1    58  |*36   2      569
9      135    35   | 2   6    7   | 34   145    8
13568  2     *3568 | 39  4    58  | 7    156    159-6
-------------------+--------------+-------------------
4      368    1    | 5   37   2   | 9    3678   67
36     369    2    | 8   379  14  | 5    13467  1467
7      3589   358  | 6   39   14  | 2    1348   14 


I would also use the UR on 14s. between these two it is pretty much wrapped up.
Code: Select all
1568   14568  568  | 7   58   3   | 468  9      2
2358   3458   9    | 1   258  6   | 48   457    457
2568   568    7    | 4   258  9   | 1    56     3
-------------------+--------------+-------------------
3568   7      4    | 39  1    58  | 36   2      569
9      135    35   | 2   6    7   | 34   145    8
13568  2      3568 | 39  4    58  | 7    156    1569
-------------------+--------------+-------------------
4      368    1    | 5   37   2   | 9    3678   67
36     369    2    | 8   379 *14  | 5    13467 *67-1-4
7      3589   358  | 6   39  *14  | 2    1348  *14 
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Postby fredooi » Mon Aug 18, 2008 11:00 pm

thank you, pat and wintder! the methods are useful, and it's really hard to see out. this puzzle was rated "diabolical" in the papers, one of two in the sunday's paper which is the harder one. feels great to have solve it. lets hope i can do it on my own come the next sunday.
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Re: hard puzzle for solving again! number 3.

Postby tarek » Tue Aug 19, 2008 6:26 am

wintder wrote:I'd use the skyscraper, also known as sashimi x-wing ...
Every now & then, I feel obliged to remind everybody that there is a preferance towards using the word sashimi in conjunction with the finning status of the fish. General use & several popular solver programs however haven't followed it.

Xwing is fine and includes what you are trying to describe
Finned X wing is even better
Sashimi Finned X-wing is more complete.

There has been a long discussion on the ultimate fish guide regarding redundancy of terms. This has provided a good excuse for everybody to stay as they are:( .

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re: terminology

Postby Pat » Tue Aug 19, 2008 8:52 am

        re: terminology
well, wintder quite properly called it a skyscraper,
and as he noted, it is also a type of turbot;
another possible interpretation is: a combination of 2 finned X-wings.

regarding those finned X-wings --

tarek wrote:Xwing is fine and includes what you are trying to describe

Finned X wing is even better

Sashimi Finned X-wing is more complete.

  1. the term "X-wing" on its own -- without stating "finned" or "sashimi" -- implies unfinned;
    therefore i consider it unacceptable for finned.
  2. some call them finned, others prefer sashimi, and you prefer Sashimi Finned -- so yes the only agreement is that we each stay with our own preference---
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Postby wintder » Tue Aug 19, 2008 9:04 am

Thanks Pat.

I'll expand for those who might wonder what the differences are:

Using simple cases and all vertical examples and considering the eliminations for the "head" only there are several distinct examples of "grouped x-wing", Havard's preferred choice of naming for this set of patterns.
I prefer to keep to the "proper" names, and use them (as does Ruud's sudoku cue). In a dog show all entrants are "dogs" but it is usefull to distinguish the breeds when comparing them.

Here "#" will denote a member cell of the pattern and "~" denotes a cell that cannot be the same value as the pattern. "*" denotes a cell that must have the candidate value of the pattern made unavailable. (As I said, I am only showing eliminations caused by the "head", because when a single tower holds the pattern the "feet" become involved in eliminations in all of these patterns.) (A tower is 3 stacked boxes, the patterns shown here use 2 of the 3 towers.)

Code: Select all
This is an x-wing. It has exactly 4 cells and can cause 7 eliminations.

+-----------------------------------+
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  *  *  #  |  *  *  #  |  *  *  *  |
|-----------+-----------+-----------|
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|-----------+-----------+-----------|
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  #  |  .  .  #  |  .  .  .  |
+-----------------------------------+

This is one of the two finned x-wings.  This time there are 6 cells in the pattern and just 2 possible eliminations.

+-----------------------------------+
|  .  .  #  |  .  .  ~  |  .  .  .  |
|  .  .  #  |  .  .  ~  |  .  .  .  |
|  *  *  #  |  .  .  #  |  .  .  .  |
|-----------+-----------+-----------|
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|-----------+-----------+-----------|
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  #  |  .  .  #  |  .  .  .  |
+-----------------------------------+

The other basic finned x-wing, 5 cells and 2 elimination cells.

+-----------------------------------+
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  #  |  .  .  ~  |  .  .  .  |
|  *  *  #  |  .  .  #  |  .  .  .  |
|-----------+-----------+-----------|
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|-----------+-----------+-----------|
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  #  |  .  .  #  |  .  .  .  |
+-----------------------------------+

The basic sashimi x-wing. 4 cells in the pattern, 4 cells for possible eliminations.

+-----------------------------------+
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  #  |  *  *  ~  |  .  .  .  |
|  *  *  ~  |  .  .  #  |  .  .  .  |
|-----------+-----------+-----------|
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|-----------+-----------+-----------|
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  #  |  .  .  #  |  .  .  .  |
+-----------------------------------+

The finned sashimi, exactly 5 cells to the pattern, 2 cells can have eliminations.

+-----------------------------------+
|  .  .  #  |  .  .  ~  |  .  .  .  |
|  .  .  #  |  .  .  ~  |  .  .  .  |
|  *  *  ~  |  .  .  #  |  .  .  .  |
|-----------+-----------+-----------|
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|-----------+-----------+-----------|
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  #  |  .  .  #  |  .  .  .  |
+-----------------------------------+

X-wing, finned x-wing, sashimi x-wing, and finned-sashimi x-wing are all distinct. When they are appropriately named information is added.
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Re: re: terminology

Postby tarek » Tue Aug 19, 2008 9:20 am

Pat wrote:the term "X-wing" on its own -- without stating "finned" or "sashimi" -- implies unfinned;
therefore i consider it unacceptable for finned
That is exactly what I was trying to change (and failed) --- I prefer (dropping the word unfinned is optional). x-wing to me means a 2-fish ( finned/unfinned sashime/nonsashimi). I have settled with the fact that evrybody seems to be happy with how things are at the moment.

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Postby ronk » Tue Aug 19, 2008 9:24 am

wintder wrote:
Code: Select all
The basic sashimi x-wing. 4 cells in the pattern, 4 cells for possible eliminations.

+-----------------------------------+
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  #  |  *  *  ~  |  .  .  .  |
|  *  *  ~  |  .  .  #  |  .  .  .  |
|-----------+-----------+-----------|
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|-----------+-----------+-----------|
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  #  |  .  .  #  |  .  .  .  |
+-----------------------------------+

The finned sashimi, exactly 5 cells to the pattern, 2 cells can have eliminations.

+-----------------------------------+
|  .  .  #  |  .  .  ~  |  .  .  .  |
|  .  .  #  |  .  .  ~  |  .  .  .  |
|  *  *  ~  |  .  .  #  |  .  .  .  |
|-----------+-----------+-----------|
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|-----------+-----------+-----------|
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  ~  |  .  .  ~  |  .  .  .  |
|  .  .  #  |  .  .  #  |  .  .  .  |
+-----------------------------------+

X-wing, finned x-wing, sashimi x-wing, and finned-sashimi x-wing are all distinct. When they are appropriately named information is added.

Interesting point-of-view, but I know of no one else that makes such a distinction.
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