Die Schwalbe

1 problem(s) found in 3906 milliseconds (displaying 1 problem(s)). [PROBID='P0002475'] [download as LaTeX]

1 - P0002475
Andrej N. Kornilow
Die Schwalbe 99 06/1986
P0002475
(12+12)
h#3 (PR&AP)
Weiß zieht an
hans: 1. ... b5xc6/ep 2. a7-a6 Sb8xa6 3. 0-0-0 Sa4-b6#
It’s possible to make c7-c5 black’s last move (not forced) Is that what (PR&AP) means? (2012-08-06)
Henrik Juel: PR should probably be PRA=partial retrograde analysis, meaning that the solution play comes in (here) two parts. Nowadays it is called RV=retro variants, I believe.
AP=a posteriori means that an ep capture may be legitimized by a later castling.
If Ke8 has not moved, last move was c7-c5 or e7-e5, corresponding to the two parts:
1... bxc6ep 2.a6 Sxa6 3.0-0-0 Sb6#
1... fxe6ep 2.Sxh6 Sc6 3.0-0 Se7# (2012-08-06)
Henrik Juel: In the second part 1... fxe6ep? 2.Kf8 Sc6 3.Te8 Lg7 is just a try, because the ep capture has not been legitimized.
Unfortunately there is no such try in the first part (2012-08-06)
Ladislav Packa: In the problem P0003447 the move right 0-0-0 is 2 times acknowledged, but not executed.
(The problem shows PRA convention, not AP.) (2012-08-06)
VL: This problem was published in the article entitled "Die partielle Synthese in Retroproblemen" (problem G). It deliberately combines bad compatible logics of pRA and AP (a kind of retrosynthese) being unsound (no solution!) under each logic applied separately.

To become sound, this "hybrid" problem is considered under an ad hoc (and rather weird) combination of AP with restricted pRA (of "Typ Oeffner" = PR). Namely, the pRA logic covers here ONLY the starting choice between the two
ep-keys, so that every ep-capture creates a partial solution. But the very availability of such a choice should be justified in the spirit of AP in order to exclude the last move by bK! The ordinary AP-facilities (subsequent
actual castling) are used, this time, however, implemented in every partial solution. The wording in the article: Eine beliebige schwarze Rochade legalisiert irgendeinen von zwei E.p.-Schlaegen. A similar reasoning is needed in order to ensure the soundness of P0002476 (stipulated "Einheitsloesung! (PR&AP)"). (2012-08-26)
comment
Keywords: Castling (sg), En passant as key, a posteriori (AP)
Genre: h#, Retro
FEN: rN2k1nr/p2p3p/7P/PPpKpPP1/N1P1P1pP/2B4p/2p5/8
Input: Gerd Wilts, 1995-06-03
Last update: A.Buchanan, 2020-12-08 more...
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