October 25, 2019

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October 25, 2019

Postby ArkieTech » Fri Oct 25, 2019 11:21 am

Code: Select all
 *-----------*
 |.6.|...|3..|
 |...|.7.|54.|
 |1.3|4.2|9..|
 |---+---+---|
 |5..|.24|...|
 |.2.|.5.|.3.|
 |...|91.|..4|
 |---+---+---|
 |..9|8.1|4.5|
 |.16|.4.|...|
 |..5|...|.7.|
 *-----------*

.6....3......7.54.1.34.29..5...24....2..5..3....91...4..98.14.5.16.4......5....7.



Play/Print this puzzle online
dan
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Re: October 25, 2019

Postby rjamil » Fri Oct 25, 2019 11:46 am

Hi ArkieTech,

First of all, many thanks for including the puzzle in line format!!!

Old wrong step:
Hidden Text: Show
Code: Select all
 +---------------+--------------+------------------+
 | 47   6   47   | 15  89   59  | 3     128   128  |
 | 9    8   2    | 16  7    3   | 5     4     (16) |
 | 1    5   3    | 4   68   2   | 9     (6)8  7    |
 +---------------+--------------+------------------+
 | 5    9   17   | 3   2    4   | 167   168   168  |
 | 467  2   1478 | 67  5    678 | 17    3     9    |
 | 367  37  78   | 9   1    678 | 2     5     4    |
 +---------------+--------------+------------------+
 | 237  37  9    | 8   36   1   | 4     2(6)  5    |
 | 23   1   6    | 57  4    57  | 8     9     23   |
 | 8    4   5    | 2   369  69  | (16)  7     36-1 |
 +---------------+--------------+------------------+

W-Wing: 16 @ r2c9 r9c7 SL 6 @ r3c8 r7c8 => -1 @ r9c9; stte

Code: Select all
 +---------------+-------------------+-----------------+
 | 47   6   47   | 15    89      59  | 3     128  128  |
 | 9    8   2    | 1[6]  (7)     3   | 5     4    (16) |
 | 1    5   3    | 4     [6]8    2   | 9     68   7    |
 +---------------+-------------------+-----------------+
 | 5    9   17   | 3     2      4    | 167   168  168  |
 | 467  2   1478 | 67    5      678  | 17    3    9    |
 | 367  37  78   | 9     1      678  | 2     5    4    |
 +---------------+-------------------+-----------------+
 | 237  37  9    | 8     3[6]   1    | 4     26   5    |
 | 23   1   6    | 57    4      57   | 8     9    23   |
 | 8    4   5    | 2     (369)  [6]9 | (16)  7    36-1 |
 +---------------+-------------------+-----------------+

W-Wing: 16 @ r2c9 r9c7 ERI 6 @ b2r2c5 ERI 6 @ b8r9c5 => -1 @ r9c9; stte

R. Jamil
Last edited by rjamil on Fri Oct 25, 2019 8:02 pm, edited 3 times in total.
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Re: October 25, 2019

Postby Ngisa » Fri Oct 25, 2019 12:54 pm

Code: Select all
+-------------------+--------------------+-------------------+
| 47     6     47   |c15     89     c59  | 3      128    128 |
| 9      8     2    |b16     7       3   | 5      4     a16  |
| 1      5     3    | 4      68      2   | 9      68     7   |
+-------------------+--------------------+-------------------+
| 5      9     178  | 3      2       4   | 167    168    168 |
| 467    2     1478 | 67     5       678 | 17     3      9   |
| 367    37    78   | 9      1       678 | 2      5      4   |
+-------------------+--------------------+-------------------+
| 237    37    9    | 8      36      1   | 4      26     5   |
| 23     1     6    | 57     4       57  | 8      9      23  |
| 8      4     5    | 2      369    d69  |d16     7      36-1|
+-------------------+--------------------+-------------------+

(1)r2c9 = r2c4 - (1=59)r1c46 - (9=61)r9c67 => - 1r9c9; stte

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Re: October 25, 2019

Postby SpAce » Fri Oct 25, 2019 4:02 pm

Code: Select all
.---------------.---------------.----------------------.
| 47   6   47   | 15   89   59  | 3      128   a1[2]-8 |
| 9    8   2    | 16   7    3   | 5      4      16     |
| 1    5   3    | 4   b68   2   | 9   ad[6](8)  7      |
:---------------+---------------+----------------------:
| 5    9   17   | 3    2    4   | 167    18-6   168    |
| 467  2   1478 | 67   5    678 | 17     3      9      |
| 367  37  78   | 9    1    678 | 2      5      4      |
:---------------+---------------+----------------------:
| 237  37  9    | 8   c36   1   | 4    bd2(6)   5      |
| 23   1   6    | 57   4    57  | 8      9     b23     |
| 8    4   5    | 2    369  69  | 16     7      136    |
'---------------'---------------'----------------------'

(26)b3p38 = (26)b9p62|(6)r3c5 - r7c5 = (68)r73c8 => -6 r4c8, -8 r1c9; stte
-SpAce-: Show
Code: Select all
   *             |    |               |    |    *
        *        |=()=|    /  _  \    |=()=|               *
            *    |    |   |-=( )=-|   |    |      *
     *                     \  ¯  /                   *   

"If one is to understand the great mystery, one must study all its aspects, not just the dogmatic narrow view of the Jedi."
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Re: October 25, 2019

Postby SpAce » Fri Oct 25, 2019 4:25 pm

Hi rjamil,

rjamil wrote:W-Wing: 16 @ r2c9 r9c7 SL 6 @ r3c8 r7c8 => -1 @ r9c9; stte

There's no strong link on 6s in column 8 (looks like you missed r4c8). Thus no W-Wing.

In fact, I don't think Dan posts puzzles that are solvable with a single non-grouped W-Wing (too easy), so you should probably suspect that you've made a mistake if you think a W-Wing does solve one of his. The same is true with a few other simple patterns like the XY-Wing, XYZ-Wing, finless basic fishes, non-grouped Turbot Fishes (and longer non-grouped X-Chains too as per latest agreement). Other one-letter wing types (M,L,S,H) still work, because they're not considered as trivial and common as the ubiquitous W-Wings and Y-Wings.
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Re: October 25, 2019

Postby eleven » Fri Oct 25, 2019 5:35 pm

SpAce wrote:
rjamil wrote:W-Wing: 16 @ r2c9 r9c7 SL 6 @ r3c8 r7c8 => -1 @ r9c9; stte

There's no strong link on 6s in column 8 (looks like you missed r4c8).

They are strongly linked by the x-wing - which neither was mentioned nor shown in the grid.
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Re: October 25, 2019

Postby Sudtyro2 » Fri Oct 25, 2019 6:39 pm

Code: Select all
+---------------+---------------+-----------------+
| 47  6   47    | a15   89  59  |  3    b128  128 |
| 9   8   2     |  16   7   3   |  5     4    16  |
| 1   5   3     |  4    68  2   |  9     68   7   |
+---------------+---------------+-----------------+
| 5   9   17    |  3    2   4   |  167  c168  168 |
| 467 2   1478  | e67   5   678 | d17    3    9   |
| 367 37  78    |  9    1   678 |  2     5    4   |
+---------------+---------------+-----------------+
| 237 37  9     |  8    36  1   |  4     26   5   |
| 23  1   6     | f7-5  4   57  |  8     9    23  |
| 8   4   5     |  2    369 69  |  16    7    136 |
+---------------+---------------+-----------------+

(5=1)r1c4 - r1c8 = r4c8 - (1=7)r5c7 - r5c4 = (7)r8c4 => -5 r8c4; stte

Btw, can anyone solve UR(37)r67c12 using just the two internals?
[Thx to SpAce for his solution posted below]

SteveC
Last edited by Sudtyro2 on Sat Oct 26, 2019 9:54 am, edited 1 time in total.
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Re: October 25, 2019

Postby rjamil » Fri Oct 25, 2019 7:44 pm

Hi SpAce and eleven,

eleven wrote:
SpAce wrote:
rjamil wrote:W-Wing: 16 @ r2c9 r9c7 SL 6 @ r3c8 r7c8 => -1 @ r9c9; stte

There's no strong link on 6s in column 8 (looks like you missed r4c8).

They are strongly linked by the x-wing - which neither was mentioned nor shown in the grid.

Accept apology for my blunder mistake. I am extremely sorry.

Actually, the puzzle solves in two steps. There is one row wise X-Wing 6 @ r37c58 step before W-Wing move that eliminates 6 from r4c8. However, just checking the puzzle by simply omitting X-Wing and advances with W-Wing elimination performs manually, puzzle solved. I wrongly assume that the W-Wing move alone solves the puzzle as OTP.

Now I realize that what I made a mistake by omitting X-Wing move.

Thanks for the correction. By the way, I have checked with another Strong Link of the same W-Wing that works perfectly as OTP.

R. Jamil
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Re: October 25, 2019

Postby Cenoman » Fri Oct 25, 2019 8:17 pm

Code: Select all
 +--------------------+---------------------+--------------------+
 |  47*   6    47*    |    15   89    59    |  3     128   128   |
 |  9     8    2      |   c16   7     3     |  5     4    d16    |
 |  1     5    3      |    4    68    2     |  9     68    7     |
 +--------------------+---------------------+--------------------+
 |  5     9    17     |    3    2     4     |  167   168   168   |
 | a467*  2   A1478*  | Bba67#  5    C678*  | B17    3     9     |
 |  367   37   78*    |    9    1    C678*  |  2     5     4     |
 +--------------------+---------------------+--------------------+
 |  237   37   9      |    8    36    1     |  4     26    5     |
 |  23    1    6      |    57   4     57    |  8     9     23    |
 |  8     4    5      |    2    369  D69    | E16    7     36-1  |
 +--------------------+---------------------+--------------------+

MUG (478)r1c13, r5c136, r6c36 using mixed internals-external
(7r5c4|6r5c1) - (6)r5c4 = r2c4 - (6=1)r2c9
(1)r5c3 - (1=76)r5c47 - r56c6 = r9c6 - (6=1)r9c7
=> -1 r9c9; ste
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Re: October 25, 2019

Postby SpAce » Sat Oct 26, 2019 2:13 am

Hi Steve,

Sudtyro2 wrote:Btw, can anyone solve UR(37)r67c12 using just the two internals?

Yes, but it's not pretty. The problem is that they're both true candidates but 6r6c1 doesn't solve the puzzle with basics when placed. It means that a second level of branching is inevitable. Ideal guardians contain only true stte/btte-candidates and false ones, because the latter is usually easier to bend to your will than ineffective true candidates.

Here's one way to do it:

Code: Select all
(2)r7c1 - (2=61)b9p27
||
(6-3)r6c1 = (3,7)r67c2 - (7)r7c1
                         ||
                         (3)r7c1 - (3=6)r7c5 - r3c5 = (61)b3p86
                         ||
                         (2)r7c1 - (2=61)b9p27


=> -1 r9c9; stte

As we've seen, there are much simpler ways to get the same elimination with the same end points, so the UR complication doesn't make much sense.
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Re: October 25, 2019

Postby SpAce » Sat Oct 26, 2019 2:35 am

rjamil wrote:Accept apology for my blunder mistake. I am extremely sorry.

No need to apologize. Mistakes are the best teachers!

By the way, I have checked with another Strong Link of the same W-Wing that works perfectly as OTP.

The logic works, but it's not a W-Wing. Too many links for that. Remember that all one-letter wings have exactly three strong links. This has four:

W-Wing: 16 @ r2c9 r9c7 ERI 6 @ b2r2c5 ERI 6 @ b8r9c5 => -1 @ r9c9; stte

The same as a chain:

(1=6)r2c9 - r2c4 = r3c5 - r79c5 = r9c6 - (6=1)r9c7 => -1 r9c9

Or:

(1=6)r2c9 - r2c4 = r3c5 - r7c5 = r9c56 - (6=1)r9c7 => -1 r9c9

Even with fewer links it wouldn't be a simple W-Wing because of the group node in box 8 (you should use the "Grouped" prefix to denote that). You could perhaps call that an Extended Grouped W-Wing or something, but it's probably not very standard. The group node (and the corresponding prefix) can also be avoided with either of these:

(1=6)r2c9 - r2c4 = r3c5 - r7c5 = r7c8 - (6=1)r9c7 => -1 r9c9 (yours without the group node)
(1=6)r2c9 - r3c8 = r3c5 - r7c5 = r7c8 - (6=1)r9c7 => -1 r9c9 (the X-Wing path mentioned by eleven)

ERIs (with more than two candidates) and other group links should normally be used only when simple links aren't available. Otherwise they're just unnecessary complications in the chain form. Also if such group links are used with a named pattern, it should be mentioned with the "Grouped" qualifier to warn the reader to look for such links instead of the simple form.

(On the other hand, more specific type designators are not necessary or even helpful for most readers. Everyone knows what "grouped" means, and it's useful information, but few know or care what something arbitrary like "Type 6B" means.)
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Re: October 25, 2019

Postby rjamil » Sat Oct 26, 2019 3:56 pm

Hi SpAce,

SpAce wrote:Even with fewer links it wouldn't be a simple W-Wing because of the group node in box 8 (you should use the "Grouped" prefix to denote that). You could perhaps call that an Extended Grouped W-Wing or something, but it's probably not very standard.

Ok. As per discussion here, I will prefer to use Grouped prefix for Empty Rectangle(s) as strong/weak links in W-Wing moves.

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Re: October 25, 2019

Postby SpAce » Sat Oct 26, 2019 5:09 pm

rjamil wrote:Ok. As per discussion here, I will prefer to use Grouped prefix for Empty Rectangle(s) as strong/weak links in W-Wing moves.

Not really sure what you mean. The "Grouped" prefix is indeed correct for a W-Wing that uses an ERI (with more than two candidates) as the location strong link, but it's also correct when a line-based group link is used. There can be only one such ERI, though, or you have too many links to call it a W-Wing. If you're again talking about the horrible "Grouped ER" term, feel free to do so. I also feel free to ignore such stupid ideas that willfully spread ambiguity and confusion. There's only one widely accepted meaning for "Grouped" and it's not "Grouped ER". The latter meaning should be dropped.
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