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| | Page: [Previous] [Next] 1 2 3 | | (41) Posted by Jacques Rotenberg [Tuesday, Jan 14, 2014 08:33]; edited by Jacques Rotenberg [14-01-14] |
Dominique wrote the solution in French, I translate :
1…Rd8 2.Tç5 Ré8 3.g8=D‡ means
1…Kd8 2.Rc5 Ke8 3.g8=Q‡
If 3.g8=R+? Ra8 plays ! And the king is safe
See (17)
Btw perhaps it should be needed to indicate "Disparate Rex exclusive" in order not to have 1.Kh6 2.Kg7 3.Kf8#
Or also put the white rook and king down, say Rf1 & Kh1 in the diagram.
| | | (42) Posted by Andrew Buchanan [Tuesday, Jan 14, 2014 17:25] |
Sorry I was sleepily thinking about the conventions more than the chess. In the second diagram in 38, there are 3 PRA options:
(a) Black moved K last, White can move P or R, Black can't castle.
(b) Black moved R last, White can move P or K, Black can't castle.
(c) Black moved P last, White can move K or R, Black has castling rights (but never can castle).
(a) & (b) allow 1.g7! key
(b) & (c) allow Jacques' 1.Kh6! key
I sort of see the different PRA options in a direct mate as like Black defences. So as long as each White mate appears as a unique response to *some* PRA option, the problem is somehow sound. The fact that (b) admits two White keys is not a fatal defect.
Cheers,
Andrew.
| | | (43) Posted by Andrew Buchanan [Tuesday, Jan 14, 2014 17:32] |
I also am getting Disparate & Fuddled Men mixed in my head!
| | | (44) Posted by Valery Liskovets [Thursday, Jan 16, 2014 09:02] |
This topic is close to my old interests and research. A fruitful discussion in general with spectacular examples.
Andrew, I share practically everything you wrote here, very transparently and convincingly. Some supplements and comments.
Post (34). Presently I know definitely only two elements that are to be regulated by "police court": e.p. and the turn to move (maybe treated more generally in fairies).
Post (37). Indeed, in fairy chess, RS can create unusual entanglements of retro-elements. In particular, in the genre "retro-volages". I composed several such problems; see, e.g.:
http://pdb.dieschwalbe.de/search.jsp?expression=PROBID=%27P0008509%27
http://pdb.dieschwalbe.de/search.jsp?expression=PROBID=%27P1083543%27 ,
where one move (or several ones) MAKES LEGAL another move of the same or opposite side,
http://pdb.dieschwalbe.de/search.jsp?expression=PROBID=%27P0008506%27
with a kind of the BURIDAN-ASS PARADOX (one out of two moves is legal potentially but we don't know which one, so that any of them is illegal as the first move because of auto-check) and
http://pdb.dieschwalbe.de/search.jsp?expression=PROBID=%27P0008520%27
with the same collision in grotesque form. (To my regret, the texts describing these problems in the PDB have been slightly corrupted; in particular, rooks are denoted both by R and T.)
Post (29). Historical remarks. The general unifying idea for pRA and RS implemented in the current Codex was first proposed by me in the article AN ORDER IN CONTROVERSIAL RETRO-GENRES, "Shakhm. Kompoz.", 1993, No.6, p.58-60 (in Russian; elaborated in reality long before). Concentrated around "the SOLVABILITY PRESUMPTION". Much later W.Keym in a long e-mail correspondence with me offered its current simplified 2-element form (in my article I consider a version that contains a refined sequence of 3 controversial genres...).
I know of no old RS-problems that would become unsound under the current Art.16. On the other hand, its appearance in this wording facilitated W.Keym in composing a few challenging RS-problems with 4 castlings (formerly Werner was a firm opponent of the retro-strategy).
Post (31). In pRA problems, for "non-dominated states" I (offer to) use the term "RETRO-VARIANTS" (RV).
| | | (45) Posted by Andrew Buchanan [Friday, Jan 17, 2014 18:20] |
Phew! Thanks Valery, I'm glad I got it mostly right! I will reply more thoroughly later in the weekend. By the way, out of the blue I got an email from Ronald Turnbull after many years! Again, I will reply to him over the weekend.
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