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MatPlus.Net Forum Retro/Math Last-Move PGs

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Thanks for the warm comments, Per. This is the closest to an orthodox proof game showing a Queen Schnoebelen, that I could think of. The Queen promotion was necessary in order to control e2, and, of course, to check the white King. I believe that a stipulation like 9.RxQf1# would be unacceptable, because it defines the Queen promotion. In this case, a Queen Schnoebelen could be achieved in only 5 moves with something like: 1.d4 4.dxe7 and 5.exf8=Q+ KxQf8 (black playing something unique in the meantime).

Delaying the capture might be possible (in a different setting), but I opted for the most economical position. Not to mention that with my rusty proof game composing skills, it took me hours to achieve even this simple illustration of the idea.

Finally, for the readers who are not familiar with retro terminology, and also for the administrator, who is preparing his TnT, it seems necessary to define the Schnoebelen theme: "A promoted piece is captured without ever moving after its promotion". The only way to determine the type of the promotion in an orthodox proof game (and avoid cooks), is with the use of the opposite King. e.g. With the moves Ke1-e2 and Ke2-e3, it becomes obvious that a promoted piece on f1 is neither a Bishop/Queen (they control e2), nor a Knight (it controls e3); therefore, it must be a Rook. If this Rook is captured on f1, without moving after its promotion, we have the Schnoebelen theme. In this example, it is impossible to determine that the promoted piece is a Queen, because a Rook or a Bishop would also be possible.

For readers, who are not familiar with the world of proof games: when Kostas mentions his 'rusty proof game composing skills', then he will rank high in the competition 'Understatement of the Year'!

“A determined soul will do more with a rusty monkey-wrench than a loafer will accomplish with all the tools in a machine shop.”
-Robert Hughes (Australian art Critic and Author).

I've composed a few PGs with Kostas... if he's rusty, he's still a better bet than a pawn odds game against Paul Morphy.

Kevin says:
"You can, of course, computer-test such a proof game, by gripping the output of Natch (all solutions to PG9.0) for the last move (in this case: "9.- Qd8")"
Natch offers 847 solutions at Dani's position, but only one with 9...Qd8:
1.Sg1-f3 Pe7-e5 2.Sf3-d4 Bf8-b4 3.Pf2-f3 Bb4-c3 4.Pd2xc3 Qd8-f6 5.Bc1-g5 Qf6-b6 6.Bg5-e7 Sb8-c6
7.Be7-f8 Sc6-e7 8.Ke1-f2 Pc7-c6 9.Kf2-g3 Qb6-d8
Nice Queen's triangle....
On can make an even difficult stipulation like this: "Find the shorter PG in which a Lady made the last move"

Thanks Paul.
I said "grepping" (apologies to those unfamiliar with the Unix "grep" command), not gripping... but, of course, a simple keyword search will suffice.

Kostas, is your problem possible with the following stipulation ?

"At its 8th move, black selfmates in 1" - the bRh8 being on a5. (with no diagram, of course)

Jacques, there is at least one way to deviate from the intended solution: 5.Qg4 Rh5 or 5.Qh5 Rxh5. I suspect there are other ways, using different (self)mating positions, but I have nothing concrete to show right now.

(28) Posted by Kostas Prentos [Monday, Mar 19, 2012 19:19]

OK, here is a different solution which uses the bRa5:
1.e3 h5 2.Qxh5 g5 3.Qxg5 Rh6 4.Ke2 Ra6 5.Kf3 Ra5 6.Kf4 f5 7.f3(Sf3) Sf6 8.~ Sh5+ 9.Qxh5#

In order to avoid the random move on white's 8th, it is possible to switch colors and have white to be selfmated half a move faster, but this is still not unique.