Problems 439 & 440: Crisan & Huber - Fairy (Back to Back, neutrals)

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Problems 439 & 440: Crisan & Huber - Fairy (Back to Back, neutrals)

(09.09.2014) The Romanian duo Crisan - Huber presents us two nice fairy problems with similar mechanisms. Welcome to Eric in the KoBulChess Originals section!

439

Back-to-Back (BTB): When pieces of opposite colors stand back-to-back with each other on the same file, they exchange their roles. P on the first rank cannot move. Any piece can make an en passant capture when it is given a power to move as P by BTB.

Comments

+3 #1 Nikola Predrag 2014-09-09 12:17

439. is a wonderful rendering of strategic complexity based exactly on the applied fairy condition. Such approach reveals a true logic potential of some fairy element.

The economy appears as great but the Neutrals are actually very expensive for this idea (perhaps too expensive?).

The reciprocity of bRb1/bBa4 is tremendously enriched by dual avoidance in the virtual content.

Whatever might make the reciprocity of the Neutrals, should better not be mentioned at all.

Some reciprocity of bRe1/bBg2 would be very welcomed, at least to avoid the half-idleness but it seems quite OK for a helpmate just as it is now.

Without deep analysis, 440. looks as not a genuine hs#, as 339. so nicely proves.
The half-idleness is avoided but not enough convincingly to justify the change of genre.
(Perhaps my first impression is wrong.)

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+1 #2 Nikola Predrag 2014-09-09 13:42

Hm, the mates in 439. are not model.

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0 #3 Kjell Widlert 2014-09-24 17:21

I don't see why the mates in 439 should not be model - I see only e5 doubly guarded, but of course both checks are necessary for mate. The mates in 440, however, are obviously non model.

I prefer 439 over 440, mainly because the interferences in B2 are much more subtle than the corresponding blocks in 440. The neutrals used only for technical purposes (only Black has the time to produce the changing White guards) are a clear drawback, however. And the claimed dual avoidance does not convince me at all: Ba4-c2?? fails not only because of self-check, but also because of stopping Rc3-g3 by a BTB effect, and by leaving Rb1 in place so that even if White could play Rc3-g3+, Black could easily parry by moving Bg2 (Bb2 does not check). But this is not essential for the content, so we should simply forget about the "dual avoidance".

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0 #4 Nikola Predrag 2014-09-24 19:19

Model mates in the example below show why the mates in 439 are not model, at least I see it so:
White Sf6 Ra5 Bb2
Black Pf7 Ke5 Ba4 Bh3 Bg2 Rb1 Re1
Stipulation H#2
Condition backtoback
Twin Move f6 f5

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0 #5 Kjell Widlert 2014-09-24 19:55

You're right, Nikola!
f4 in the first solution, and f5 in the second, are in fact doubly guarded because of BTB. So your version, which eliminates the technical neutrals and ends in BTB-specific models, is to my mind definitely an improvement! (Personally, I don't mind three black bishops in a fairy, but just for the record: would it be possible to avoid them?)

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0 #6 Nikola Predrag 2014-09-24 21:56

bQh3 would be OK. Possibility of selfblock on e6 must be avoided in b), with wSf5 there's a cook:
1.block-e6 Ra5-c3 & 2.Re1-e4 Rc5#

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0 #7 Vlaicu Crisan 2014-09-26 20:57

Both I and Eric think Nikola's version of 439 is clearly superior. We would like to propose, if Nikola Predrag also accepts, to replace 439 with the version he suggested. Thank you!

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+1 #8 Nikola Predrag 2014-09-27 15:29

Hm, my comment from 9.9. was based on that quick-made example. I did not try to improve it later.
So, perhaps it could be improved. At least, you should decide about a piece on h3 (bB or bQ) and add wK as you like.

It is, of course, entirely your composition and you may consider and make use of any of my suggestions, as freely as you find it interesting.

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+1 #9 Vlaicu Crisan 2014-10-11 06:11

Nikola, we would kindly invite you to accept being a third co-author as your suggestion significantly improved its quality!

We will leave it to you to decide what piece goes on h3 (bQ or bB). Thank you very much!

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