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competition #992 plus bonus

 
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Fri Mar 28, 2008 10:09 pm    Post subject: competition #992 plus bonus Reply with quote

competition #992 from sudokulist.

Code:
...|6..|4.1
..4|3..|8..
2..|...|3.5
---+---+---
1..|.25|.46
...|...|...
92.|46.|..3
---+---+---
6.3|...|..2
..2|..6|5..
5.9|..8|...


for the fisherman, there is a jellyfish ( A.K.A. x-wing ^2 ) on the number 8 right after basics.

also of interest, two ER eliminations on 8.
----

this puzzle probaby contains eveything if you have time to look for it.

I think I count 1 xy-chain, coloring on 7, xy-wing, finned x-wing, ER, not in that order, don't want to spoil the fun.

Code:
94.|.5.|8.3
..2|...|..1
1..|..4|.9.
---+---+---
..6|2.5|...
3..|.9.|..5
...|3.6|7..
---+---+---
.3.|9..|..2
5..|...|1..
7.1|.6.|.84


-------

I will throw this 9x7 monster in here for good measure. its extreme, and I couldn't solve it. it was rated fiendish on sudokupuzz.com, right !!

Code:
...|...|...
.5.|1.7|.6.
.96|2.8|37.
---+---+---
9..|7.3|..8
..8|4.1|7..
2..|8.9|..4
---+---+---
.23|6.5|94.
.1.|3.4|.2.
...|...|...


enjoy,
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ravel



Joined: 21 Apr 2006
Posts: 536

PostPosted: Sat Mar 29, 2008 1:18 pm    Post subject: Reply with quote

The first two are nice M-wing puzzles.

The third one becomes very nice after this chain:
Code:
 *-----------------------------------------------------------*
 | 347   3478  247   | 5     39    6     | 124   189   129   |
 | 348   5     24    | 1     39    7     | 48    6     29    |
 | 1     9     6     | 2     4     8     | 3     7     5     |
 |-------------------+-------------------+-------------------|
 | 9     46    145   | 7     256   3     | 1256  15    8     |
 |*356  *36    8     | 4     256   1     | 7     359   2-369 |
 | 2     367   157   | 8     56    9     | 156   135   4     |
 |-------------------+-------------------+-------------------|
 | 78    2     3     | 6     178   5     | 9     4     17    |
 |*5678  1     9     | 3     78    4     |*568   2     67    |
 | 4567  4678  457   | 9     17    2     | 156  *1358 *367   |
 *-----------------------------------------------------------*

r5c12=36 or
r5c1=5 => r8c1<5> r8c7=5 => r9c8=8 => r9c9=3
==> r5c9<>3
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Victor



Joined: 29 Sep 2005
Posts: 207
Location: NI

PostPosted: Sat Mar 29, 2008 11:33 pm    Post subject: Reply with quote

First one, after the X-wing in 8s:
Code:

+------------+----------------+------------+
| 3  589  58 | 6   5789  279  | 4  27  1   |
| 7  56   4  | 3  B15    12   | 8  26  9   |
| 2  689  1  | 79  4789  479  | 3  67  5   |
+------------+----------------+------------+
| 1  3    7  | 8   2     5    | 9  4   6   |
| 48 45   6  | 179 179   3    | 2 A15  78  |
| 9  2    58 | 4   6     17   | 17 58  3   |
+------------+----------------+------------+
| 6  1478 3  | 5   1479  1479 | 17 189 2   |
| 48 147  2  | 179 13479 6    | 5  139 478 |
| 5  147  9  | 2   1347  8    | 6  13  47  |
+------------+----------------+------------+


More parallel universe stuff: I just can't see any M-wing as mentioned by Ravel. You can do this with a longish XY-chain but, searching for an M-wing, I noticed the following way to do it.

A <> 5 => B = 5 (considering 5s on their own - e.g. A & B are the free ends of a skyscraper)

But considering 1s: A = 1 => B = 1 (ER style). I.e. A <> 5 => B <> 5.

Ergo A <> 5 is false, etc.
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Victor



Joined: 29 Sep 2005
Posts: 207
Location: NI

PostPosted: Sat Mar 29, 2008 11:45 pm    Post subject: Reply with quote

2nd one. After removing a 7 from r8c4 (colouring), an 8 from r7c5 (ER) & a 1 from r4c5 (UR):
Code:

+------------+---------------+-----------+
| 9   4   7  | 16   5    12  | 8   26 3  |
| 68  568 2  | 678  3    9   | 4   57 1  |
| 1   568 3  | 678  278  4   | 256 9  67 |
+------------+---------------+-----------+
| 48  179 6  | 2    478  5   | 3   14 89 |
| 3   17  48 | 1478 9    178 | 26  26 5  |
| 2   19  5  | 3    148  6   | 7   14 89 |
+------------+---------------+-----------+
| 468 3   48 | 9    17   178 | 56  57 2  |
| 5   68  9  | 48   2478 278 | 1   3  67 |
| 7   2   1  | 5    6    3   | 9   8  4  |
+------------+---------------+-----------+


Nice puzzle. The two lower 48s (boxes 7 & 8) are conjugate (because of an M-wing) and you can continue colouring in any direction in 8s to solve the puzzle .
Or, if you look at the two 17s in boxes 4 & 8, you can see ER-style via box 5 that they too are conjugate (i.e. one's a 1, the other's a 7) & so you can again continue colouring in any direction with either number.
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ravel



Joined: 21 Apr 2006
Posts: 536

PostPosted: Sun Mar 30, 2008 11:59 am    Post subject: Reply with quote

In the first puzzle i saw the M-wing 15 connected by 4 strong links for 1.

But - oops - in the second puzzle i missed that the strong link for 4 in row 5 directly gives a w-wing 48 in r7c3 and r8c4, that solves the puzzle.
Instead i saw the pairs in r5c3 and r8c4 as M-wing (with strong link for 8 in column 3) to get to the same eliminations Wink
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Victor



Joined: 29 Sep 2005
Posts: 207
Location: NI

PostPosted: Sun Mar 30, 2008 7:42 pm    Post subject: Reply with quote

As you say, Ravel:
Quote:
In the first puzzle i saw the M-wing 15 connected by 4 strong links for 1.

And I thought I was good at spotting these things! - thanks
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