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MatPlus.Net  Forum General Retro h#? |
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| | | (1) Posted by Hauke Reddmann [Tuesday, Sep 29, 2020 20:41] | Retro h#?
Do you know h# problems with White to move
for retro reasons? The main problem here isn't
to come up with ideas but that the move count
doesn't work - a h#1 (as the intended v)
with White to move for me is a h#2!
 (= 2+9 )
demo
| | | (2) Posted by James Malcom [Tuesday, Sep 29, 2020 21:12] |
I know of this one that I remember seeing on PDB a couple of weeks ago-https://pdb.dieschwalbe.de/P1380195. However, it's much more "obvious" then your demo.
Norbert Geissler, The Problemist Supplement 2018, after Andrew Buchanan
h#3
 (= 10+12 )
| | | (3) Posted by Joost de Heer [Tuesday, Sep 29, 2020 21:17] |
Footnote 19 from the codex: 19. For the purpose of Article 9, the preliminary move by the unconventional party is not counted, except in help-play problems. The number of moves to be expressed in the stipulation should be the number of moves to be made by White.
So a h#2 really is 2 black and 2 white moves.
I think that once upon a time your scheme may have worked. A h#1.5 was, at some point in history, written as h#2 (0.1.1.1).
| | | (4) Posted by Andrew Buchanan [Wednesday, Sep 30, 2020 16:11] |
g='h#' and k='no legal' yields only 26 compositions, many from a single tourney in 1957.
Some of them have a single h#n retro try, but it's more common to offer an h#(n-1) retro try instead. The stipulation still works as a h#n logically, and even in 1957 the stipulation was h#n rather than h#(n-1). I.e. the composer assumes set play rather than a bonus move for White. What year did the convention appear?
There are also various compositions marked in PDB with the keyword "Whose move?" rather than "No legal last move for Black". Obviously these concepts are close, but I tend to associate "Whose move?" with problems that actually ask "Who?" or retros with a stipulation "#1". Having said that "Whose move?" is where the vast majority of these problems are hiding.
I think that the keywords can combined. I think "no legal... white/black" describes the factual situation that retro concerns eliminate one side or another moving. "Whose move?" seems to indicate that there is a single try in contention with the actual solution, and only retro concerns distinguish them. This would apply, imho, even if as here, the try is h#(n-1) rather than h#n.
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