View previous topic :: View next topic |
Author |
Message |
daj95376
Joined: 23 Aug 2008 Posts: 3854
|
Posted: Fri Oct 15, 2010 4:31 am Post subject: Puzzle 10/10/15: C XY |
|
|
Code: | +-----------------------+
| 4 . . | 8 . . | . . . |
| . 9 . | . . 4 | 3 6 8 |
| . . 8 | . . . | . 4 . |
|-------+-------+-------|
| 2 . . | . . 5 | 1 . . |
| . . . | . 8 . | . . 6 |
| . 8 . | 1 . 3 | . 7 . |
|-------+-------+-------|
| . 4 . | 3 . . | 6 1 . |
| . 6 7 | . . 8 | 5 2 . |
| . 2 . | . 4 . | . . 3 |
+-----------------------+
|
Play this puzzle online at the Daily Sudoku site |
|
Back to top |
|
|
peterj
Joined: 26 Mar 2010 Posts: 974 Location: London, UK
|
Posted: Fri Oct 15, 2010 8:07 am Post subject: |
|
|
A wing
Quote: | w-wing(79) with pseudocell ; (7=6)r3c1-(6=9)r6c1 - r6c5=r1c5 - (9=7)r1c7 ; r3c7<>7 |
|
|
Back to top |
|
|
daj95376
Joined: 23 Aug 2008 Posts: 3854
|
Posted: Fri Oct 15, 2010 8:54 am Post subject: |
|
|
Hmmm! I've had my reservations about the use of pseudo-cells, but I previously accepted them as harmless. With Peter's solution, even though I understand his intent, I'm not so sure that every use of a pseudo-cell is harmless.
Code: | w-wing(79) with pseudocell ; (7=6)r3c1-(6=9)r6c1 - r6c5=r1c5 - (9=7)r1c7 ; r3c7<>7
---------> *******************
|
The pseudo-cell exists in [c1]. One end is in [r3] and sees the elimination cell. The other end is in [r6] and sees one end of the intermediate strong link needed for the W-Wing. I'm not comfortable with calling it a "wing". With his use of a pseudo-cell, a 6-cell XY-Chain could be described as an XY-Wing with 3x pseudo-cells. That's a far stretch of the concept, but it still exists.
Code: | +--------------------------------------------------------------+
| 4 37 236 | 8 d2679 1679 | e79 5 12 |
| 17 9 12 | 5 27 4 | 3 6 8 |
| a67 5 8 | 267 3 1679 | 9-7 4 12 |
|--------------------+--------------------+--------------------|
| 2 37 346 | 467 67 5 | 1 8 9 |
| 579 1 45 | 247 8 79 | 24 3 6 |
| b69 8 46 | 1 c269 3 | 24 7 5 |
|--------------------+--------------------+--------------------|
| 8 4 9 | 3 5 2 | 6 1 7 |
| 3 6 7 | 9 1 8 | 5 2 4 |
| 15 2 15 | 67 4 67 | 8 9 3 |
+--------------------------------------------------------------+
# 44 eliminations remain
|
To me, a pseudo-cell is two cells that act as one in a house/unit. Typically in a UR scenario.
Comments! |
|
Back to top |
|
|
peterj
Joined: 26 Mar 2010 Posts: 974 Location: London, UK
|
Posted: Fri Oct 15, 2010 9:36 am Post subject: |
|
|
Danny, so first off I am definitely not wedded to the term 'pseudocell' and don't have a dogmatic view on insisting such a move is a 'wing'! I am just trying to communicate my solution.
I started using it because I noticed in this forum that people often described short xy-chains as 'xy-wings with pseudocell' and use terms like 'extended' or 'transport' as a qualifier on a pattern name.
I have since used it quite frequently on m-wing and w-wings where I have seen the 'pattern' but then one end needs a bit of work to fit the template! I feel that it describes how the solver sees his/her solution and, for a learner coming to this forum as I was/am, it might be an aid to starting to look for more complex chains. That's certainly how I started!
I agree you could apply such terms in ridiculous situations but I am not sure your xy-chain example is fair. If something has a formal name accepted by the community it should be used. AFAIK the move above does not have a formal name (other than a generic 'chain' or 'AIC') and so calling it a 'w-wing using pseudocell' is intended as a description. I suppose it's indicative rather than normative.
I think the problem becomes where to draw the line - is a pseudocell in a block somehow acceptable but not if well separated in a row or a column? I suppose one could perhaps limit the term to URs. Ultimately the only robust approach is to limit oneself to formally agreed names (by who?) and AIC or SIS descriptions - which I think would be a shame.
Interesting debate. |
|
Back to top |
|
|
tlanglet
Joined: 17 Oct 2007 Posts: 2468 Location: Northern California Foothills
|
Posted: Fri Oct 15, 2010 2:35 pm Post subject: |
|
|
Another "almost".
Quote: | AXY-wing 67-9 vertex (67)r4c5, pincers (69)r1c5 & (79)r5c6 with fin (27)r1c5; r3c6<>9
[xy-wing(67-9)=(27)ls:r1c5|r2c5]-(27=6)r3c4-(6=7)r3c1-(7=9)r3c7; |
Ted |
|
Back to top |
|
|
tlanglet
Joined: 17 Oct 2007 Posts: 2468 Location: Northern California Foothills
|
Posted: Fri Oct 15, 2010 3:02 pm Post subject: |
|
|
I agree with the comments already offered by Peter. Recently I responded here to a request by Marty on the definition of "pseudocell" and specifically questioned if it included more than two cells.
I do not have a strong leaning on the issue, but my preference is to restrict usage to ADPs and to one cell extensions (for a total of two cells) for general bivalue patterns; "transport" or "extend" would be used for multiple steps/cells.
Ted |
|
Back to top |
|
|
daj95376
Joined: 23 Aug 2008 Posts: 3854
|
Posted: Fri Oct 15, 2010 6:31 pm Post subject: |
|
|
Please forget that I mentioned the topic.
We'll leave it up to the individual to decide if the use of pseudo-cell seems appropriate in a post.
Regards, Danny |
|
Back to top |
|
|
Marty R.
Joined: 12 Feb 2006 Posts: 5770 Location: Rochester, NY, USA
|
Posted: Sat Oct 16, 2010 4:31 am Post subject: |
|
|
I played the Type 3 UR (15) with 27 pseudo cell, X-Wing (1) and XY-Wing (679), flightless with pincer transport. |
|
Back to top |
|
|
|