Original Problems, Julia’s Fairies – 2013 (I): January – April
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No.220 – h#3 by Francesco Simoni – An interesting and difficult problem with rich strategy! (JV)
Grasshopper(G): Moves along Q-lines over another unit of either color to the square immediately beyond that unit. A capture may be made on arrival, but the hurdle is not affected.
Rookhopper: As Grasshopper, but moves on Rook lines only.
Bishophopper: As Grasshopper, but moves on Bishop lines only.
No.220 Francesco Simoni
h#3 2 solutions (6+5)
Bishophopper a7, g8
Rookhopper c8, d8
Solution: (click to show/hide)
I. 1.Qe4 (Qc6 ?) Gd3 (Gf5 ?) 2.Qc6 (Qe6 ?) Sc5 (Sc1 ?) 3.BHd4 (RHd4 ?) Sd5‡
II. 1.Qg6 (Qe6 ?) Gf5 (Gd3 ?) 2.Qe6 (Qc6 ?) Sd5 (Sa2 ?) 3.RHd4 (BHd4 ?) Sc5‡
The bQ would already be able to occupy its final square c6 (or e6) on B1. However, to make W1 possible, the bQ moves first to another square, where it continues to guard both squares c6 and e6, to play in one of them in B2, and the bQ B2 move is specified by the move W1 by the grasshopper, which will guard the flight d5 (or c5) in the mate position. In B2 the bQ move allows the white guard on the other flight c5 (or d5) by the hopper c8 (or g8) with anticipatory selfpin of the bQ itself. In W2 the wS move pins the bQ and takes two flights. Finally, in B3, the hopper which jump became possible, blocks the square d4. Anti-battery pin model mates in reciprocal form. (Author)
Love this complex line play with excellent dual avoidance.
But have I seen this pin-mate previously here ?
Very nice, with clear purposes of moves by bQ in B1 and of all other moves.
The reasons why some moves must be played and why all other possible moves do not lead to solution, make the problem correct. But this is not a logical basis for dual avoidance., it is only about achieving the unique solutions.
In dual avoidance, the move which will be avoided must show full efficiency in some phase, only then the avoidance of it may look convincing.
The purpose of moves 2.Qc6/Qe6 is making a hurdle for wRHc8/wBHg8, providing the guard of squares c5/d5 on which w Knights will play and thus pin bQ. The full efficiency of 2.Qc6/Qe6 must be complemental with the guard of d5/c5 by wG. This may be a logic basis for dual avoidance:
I. 1.Qe4 Gd3 2.Qc6! Sc5 3.BHd4 Sd5‡
(… 2.Qe6? Sd5 3.RHd4 Sc5+ 4.Kxc5!?)
II. 1.Qg6 Gf5 2.Qe6! Sd5 3.RHd4 Sc5‡
(… 2.Qc6? Sc5 3.BHd4 Sd5+ 4.Kxd5!?)
A nice variety (rather than dis-analogy) are the hurdles (bBH/wS ) over which wG guards d5/c5
I agree with Nikola analysis. Infect I don’t speak in my comment about dual avoidance, but it’s important any move has at least an alternative, to motive all its effects. For example, to guard b3 and d3, White has in W2 two choices (Sc5 or Sc1). Without the choice Sc1, the pin effect of the move Sc3 becomes artificial.
Nikola says “A nice variety (rather than dis-analogy) are the hurdles (bBH/wS ) over which wG guards d5/c5”
I should like to obtain the homogeneous effect in B3 (as well as 3.BHd4), but the price to pay is a twin form moving the white Grasshopper.
Yes, the possibility of the move Sc1? apparently makes the pin effect more convincing.
The need of a hurdle on d5 for wGf5 might apparently diminish a bit the importance of the pin effect and the possibility of Sa2? looks a bit less significant.
But the moves Sc5/Sd5 MUST make a hurdle for bBHa7/bRHd8 for a selfblock on d4, bQ MUST make a hurdle for wRHc8/wBHg8 and it MUST be pinned in the end.
The simple guard of flights b3&d3/b4&c3 also must be achieved but it is actually only an efficient constructional tool for the economical presentation of a complex strategic mechanism.
Finally, it looks pretty convincing to me. Small varieties (which show imagination and skill in the construction) could be more interesting than a dogmatic pursuit of (so called) perfect analogy at any price.
Not here. I was confusing it with Julia’s problem 9. It has quite a different idea and no pin-mates.