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Problem 509: Francesco Simoni - Helpmate
(25.01.2015) The Italian expfrancesco.simoniert shows intricate line openings, unpins and pin-mates in his beautiful problem!

 

 

 

 

 

 

509. Francesco Simoni (Italy)
25.01.2015
509.1
H#2    b) Sa2-b1    (8+15)
 
a) 1.Sc1 Qxb2+ (Rxb2+?) 2.Se2 Sdf4#  [1…Rxb2+? 2.Se2 Se1?]
b) 1.Re6 Rxb2+ (Qxb2+?) 2.Re2 Se1#  [1…Qxb2+? 2.Re2 Sdf4?]

Black moves a piece twice, to indirectly unpin the mating one, with reciprocal dual avoidance for black line opening. The unpinning piece however, would avoid the mate for direct guard, so white has to check, to force the direct self-pin of the black piece and to perform so a pin mate.
In W1 there is reciprocal dual avoidance for loss of guard  ie. White could check with any of the two  units, but just what will be replaced by the mating piece as flight controller can only be chosen. (Author)
 

Comments  

 
+3 #1 Kjell Widlert 2015-01-26 22:05
The analogy between the solutions is almost, but not quite, perfect.

Part b) shows the idea clearly: the unpins Sb1--e2 and Rd6--e2 both guard one S-mate by line-opening and one by direct guard; White can compensate one of these by an anticipatory pin (=check!); and he must pin with the piece whose guarding duty is taken over by the wS in the mate.

So one solution is 1.Re6 Rxb2+! etc. The other should have been 1.Sc3 Qxb2+(!?) etc ... but Sc3 happens to close the line h8-b2! If there had been a square d0, everything would have been perfect.

To work around this limitation in the matrix, the composer had to show the S--e2 line in a twin with Sa2 - which has the drawback that e1 is guarded already in the diagram (in contrast to f4, which becomes guarded only by Black's play).

Bad luck, but I don't think there was a better option - and the problem is quite impressive anyway.
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+1 #2 Seetharaman Kalyan 2015-01-27 06:08
Quoting Kjell Widlert:
The analogy between the solutions is almost, but not quite, perfect.

If there had been a square d0, everything would have been perfect.

Good point. The effect of opening a black line for dual avoidance effect is not there in the other solution. But as you rightly mentioned it is still a very good problem!
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+1 #3 Francesco Simoni 2015-01-27 16:44
Quoting Kjell Widlert:
The analogy between the solutions is almost, but not quite, perfect ... (cut)
...
Bad luck, but I don't think there was a better option - and the problem is quite impressive anyway.


As you have pointed out, there isn't probably a better way. A larger chessboard would be useful, but... Another choice is to put the wQ in h6, but in this case I must prevent a terrific queen mate in the thematic square f4. To avoid this, a twin form by moving the wQ is also possible (a wR would be enought in this case), but I don't like this choice, because the W dual avoidance would be lost.
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+2 #4 Francesco Simoni 2015-01-27 16:48
Quote:
Good point. The effect of opening a black line for dual avoidance effect is not there in the other solution. But as you rightly mentioned it is still a very good problem!


Thanks! To clarify, I think the dual avoidance effect in a) cames out as soon as the wS moves 1. Sc1 and so it closes the line.
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+1 #5 eugene david rosner 2015-02-05 04:47
an incredibly daring and ambitious idea that is extremely well-executed! Kjell's analysis is spot on.
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