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MatPlus.Net Forum General What would you prefer in a fairy problem—illegal position, or stronger units than necessary?
 
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(1) Posted by Bojan Basic [Sunday, Jul 25, 2010 05:15]

What would you prefer in a fairy problem—illegal position, or stronger units than necessary?


Say that you have a fairy problem without fairy pieces on the board—only the condition(s) are fairy. The position is pretty heavy, and the number of promoted units on the board plus the number of pawns exceeds 8. However, it is possible to easily deal with this illegality, by simply switching one of the pawns for a stronger piece (e. g., initially there are 3 pawns and 8 rooks on the board, what is clearly illegal; however, the problem would work the same if one of the pawns were switched for a bishop, and thus a legal position would be obtained). Which version would you prefer?
 
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(2) Posted by Dan Meinking [Sunday, Jul 25, 2010 07:04]

Arguments could be made for either choice, but my preference would be to have the legal position. Think of it this way: you already have a heavy position. Another piece on-board is not going to make a difference economy-wise.

If you're swapping out the P for S or B, the choice is pretty easy. But if you have to exchange the P for a R or (especially) Q, then I might favor the illegal position.
 
 
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(3) Posted by Joost de Heer [Sunday, Jul 25, 2010 14:50]

Dan,

Would you accept other illegalities (e.g. a Koeko problem without touching pieces in the diagram position, or the pawn constellation wPa7, bPa6 in an AntiCirce problem)?

Personally, I don't care for legality in any position (yes, even orthodox), unless there is retro content.
 
   
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(4) Posted by Dan Meinking [Sunday, Jul 25, 2010 15:00]

@Joost,

I've never composed an illegal position, but I'm willing to give it a try. :-)
 
 
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(5) Posted by Hauke Reddmann [Sunday, Jul 25, 2010 17:54]

The legal one. That requirement is more basic. (Pun intended :-)

Hauke
 
 
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(6) Posted by seetharaman kalyan [Monday, Jul 26, 2010 11:58]

How about problems in genres like "Strict circe" (where captures are legal only if the rebirth is vacant !), or the 'Platzwechsel-Circe' Do any of these problems have legal position ?!!
 
   
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(7) Posted by Juraj Lörinc [Monday, Jul 26, 2010 14:52]; edited by Juraj Lörinc [10-07-26]

Some do have legal position. Proof games. :-)

Seriously, legality is generally not tested and required in fairy problems, even recent WCCTs have explicitly stated that legality should not be a question in fairy section. Yet, there are numbers of chess composers (including myself) who do try to have as legal position as possible, under the fairy rules applied.

Take as an example Anticirce: position wpa5, bpa4 is illegal under Anticirce rules (while ok in orthodox). Time to time it is possible to see judge's comment that such structure does not look good, or that it even had led to downgrading of the problem in the award.

Go figure.

That is why, finally, my answer to original question is: I am always approaching such question on a case by case basis. Depending on the play, on the visual look of the board, other used pieces, etc., I decide on one or the other. I have some soft rules (e.g. at most 8 pawns of the same colour if possible), but definitely no precise decision algorithm.

Edit: added omitted "not" in the sentence "... such structure does not look good, ..." (Anticirce example)
 
   
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(8) Posted by Bojan Basic [Wednesday, Jul 28, 2010 09:15]

Thank you all for you comments. I was aware that there was no general consensus, but I wanted to hear a few different opinions.

My personal opinion more or less similar to what is already said: an illegal position doesn’t bother me too much, but it is nice to have a legal position where possible. However, it seems to me that there is another factor which should be taken care of: the popularity of the fairy genre in question as an OTB game. Therefore, a Köko problem without touching pieces in the diagram position (to mention Joost’s example) doesn’t bother me at all—however, I might spend a word or two pointing to the illegal position in, say, Losing Chess (but certainly would not downgrade it in an award, if I were the judge).

 QUOTE 
Seriously, legality is generally not tested and required in fairy problems, even recent WCCTs have explicitly stated that legality should not be a question in fairy section.

This is an interesting point brought up. Looking at the Q&A from the 7th WCCT (fairy theme was Single Box), we find the following explanation (http://www.saunalahti.fi/~stniekat/pccc/7letter2.htm):

 QUOTE 
- If two bishops of the same color are on the board, one of them has obviously been promoted. Thus, 8 pawns on the board are illegal in this case.

Later, answering to the explicit question whether the position has to be a legal one, the director says (http://www.saunalahti.fi/~stniekat/pccc/7letter4.htm):

 QUOTE 
The history of the diagram position is irrelevant, and no theoretical or practical proof game is needed (only in the case of two Bishops of the same colour, no more than 7 pawns are allowed for the side who has them). The position must be "legal" only in the sense that it follows the definition of the chosen fairy type, e.g. for both types there should not exist on the board at any stage additional pieces to those contained in a "single box" etc. (see theme definition).

I have to admit that I don't understand the explanation above. Why would two bishops of the "same colour" (they certainly mean: both light-squared or both dark-squared) imply a maximum of 7 pawns for the side who has them (since, as said, "one of them has obviously been promoted"), but, say, a pawns on e2 and g2 and a white light-squared bishop somewhere else on the board would not imply a maximum of 7 pawns (although in this case it is also true that the bishop has obviously been promoted)? I don't understand the meaning of the word "obviously" used in the contest above.
 
   
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(9) Posted by Juraj Lörinc [Wednesday, Jul 28, 2010 11:50]

Fair point, Bojan, about single box problems (as the WCCT fairy section where legality was (partially) investigated). I have no precise explanations to inconsistencies raised by you, just let's say 7th WCCT was happily closed without these points raising any controversies.

In my reference to unquestioned legality in fairy sections of WCCT I had in mind the 6th WCCT (see Lacny's 7-fold Djurasevic cycle with 42 pieces on the board that have got 9th place as a conscious effort to drill as much as possible from fairy elements avilable by any means - http://jurajlorinc.tripod.com/chess/cycblank.htm#uloha13) and the the 8th WCCT (see full Q&A, at the bottom, http://www.saunalahti.fi/~stniekat/pccc/8qa.htm).
 
 
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MatPlus.Net Forum General What would you prefer in a fairy problem—illegal position, or stronger units than necessary?