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No.706, 706.1 |
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No.706 by Andreas Thoma – Remis-pendulum in Proca Retractor! (JV)
No.706.1 by Andreas Thoma – Improved version of No.706! (JV)
Definition:
Anti-Circe: After a capture the capturing piece (Ks included) must immediately be removed to its game array square (necessarily vacant, else the capture is illegal). R, B & S go to the square of the same colour as the capture; Ps stay on the file of capture; fairy pieces go to the promotion square of the file of capture.
Proca Retractor: In Retractors, White and Black retract (take back) a given number of moves (-n moves), in order to reach a position in which a forward stipulation (e.g. #1, s#1) is met. Proca is a defensive retractor. Given a choice, Black will retract those moves that avoid or delay White’s goal. Black may defend by mating White through a forward move, if such an opportunity exists after one of Black’s retractions. Unless otherwise specified, forward defense is the default condition of Proca retractors.(def. from StrateGems, http://strategems.net/sections/variant-definitions.html)
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No.706 Andreas Thoma |
Solution: (click to show/hide) |
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white ke1 Be7
black ke5 Pe6f5h6h7
-8 & #1 Proca Retractor (2+5) |
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No.706.1 Andreas Thoma |
Solution: (click to show/hide) |
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white ke1 Be7
black ke5 Bh3 Pd5e6f5h6h7
-8 & #1 Proca Retractor (2+7) |
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The rebirth after capture is missing from the solution, as well as the various checks from black. Moreover I prefer negative numbers to denote the backward sequence, but it is not mandatory. This way the solution stands:
-1.Kg5xSh5(Ke1) Sg7-h5+ -2.Kh5-g5 Se8-g7+ -3.Kg4-h5 Sg7-e8+ -4.Kh5-g4 Se8-g7+ -5.Kg4-h5 Sg7-e8+ -6.Kh5-g4 Se8-g7+ -7.Kg4-h5 f7/f6-f5+ -8.Kf3-g4 & 1.Ke4#
I think the intended solution doesn’t work. The pendulum actually starts earlier, after 2nd white move, with wKh5 and bSg7. Therefore 6.Kh5-g4?? is not legal, because the same position is repeated the third time.
Oh dear, you are right of course. That’s why the Proca-retro composers say that White must not start the pendulum play.
Further explaination: when White retracts 6.Kh5-g4, we find that this exact position occurred for the third time when (following the play forward from that point) White played 3.Kg4-h5 – which in problem chess means that the game immediately and automatically would be drawn, so that we could never have reached the diagram position. This, as Vlaicu says, in fact implies that the retraction 6.Kh5-g4?? is illegal. White falls for the same trick that he tries to use on Black!
706.1 Joint with who?
sorry, a mistake, removed!