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MatPlus.Net Forum Helpmates Bror Larsson, Springaren 1947
 
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(21) Posted by Arno Tungler [Wednesday, Jul 4, 2012 14:36]

And what was Black's last move...?
 
   
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(22) Posted by Milan Velimirović (+) [Wednesday, Jul 4, 2012 17:54]

Sorry, I gave the wrong position. I made the correction in post #20.

... but I was wrong anyway (-1.Rg4-g6+ Pg3-g4!) - please ignore my stupidity!
 
   
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(23) Posted by Jacques Rotenberg [Wednesday, Jul 4, 2012 23:20]; edited by Jacques Rotenberg [12-07-05]

another way, with a slightly different mate

(= 4+9 )

1.h×g3 e.p.+ f3+ 2.Kf4 Sf2 3.Se5 S×h3#
with the "try" 1.Rg3? f3+
 
   
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(24) Posted by Miodrag Mladenović [Thursday, Jul 5, 2012 07:57]; edited by Miodrag Mladenović [12-07-05]

I like more the other checkmate without capturing of bRh3. So it's better to have bPg6 instead of bSg6. I like this position the most:

(= 4+9 )

H#3 (4+9)

1.fg3x(ep) f3+ 2.Kf4 Sf2 3.g5 Sd3#
 
   
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(25) Posted by Nikola Predrag [Thursday, Jul 5, 2012 10:02]; edited by Nikola Predrag [12-07-05]

The last black move before the diagram has a better function if Sxh3 is mate.
 
   
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(26) Posted by Jacques Rotenberg [Thursday, Jul 5, 2012 14:18]

... a kind of "black sacrifice through the mirror".

Though captures of black units may be seen in direct mates often as rather crude, in helpmates, it is the opposite, I think.

However all that are (very) minor details.
 
   
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(27) Posted by Nikola Predrag [Thursday, Jul 5, 2012 15:51]

Captures of black pieces in a help-genre I see as more crude than in direct problems. Black and White are friends and Black is ready to sacrifice his life for the friend. Any trivial brutality on the 'body' of such a devoted friend is disgusting, it's like 'He's gonna die anyway so let's torture him before that'. Good and deep reason for a capture of a black piece is a kind of a precise surgery, which does only what is necessary, leaving everything else unharmed.

A retro-component of this problem is slightly stronger if the mate is SxRh3, because it gives more importance to the penultimate white move before the diagram. Of course, if I saw everything correct, which is far from being certain:).
 
   
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(28) Posted by Jacques Rotenberg [Thursday, Jul 5, 2012 16:11]; edited by Jacques Rotenberg [12-07-05]

What a nice poetry Nikola !

The way I understand things is much less imaginative :

In a helpmate black and white go to the same aim, black units are usually most useful to help white to give mate : they may block their King, they may close lines (black or white if needed), so a capture of a piece that - in fine - has to be seen as a help is a kind of paradox either
 
   
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(29) Posted by Nikola Predrag [Thursday, Jul 5, 2012 16:56]

The more complex the reason/motivation, the more interesting black sacrifice. But a capture of a static black piece which guards the mate is hardly a paradox. I see the things as very, very relative (I'm sure you do too). A 'Maslar' sacrifice is for instance, beautiful - a precise surgery:).
 
   
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(30) Posted by Jacques Rotenberg [Thursday, Jul 5, 2012 22:28]

"The more complex the reason/motivation, the more interesting..." yes, in general it is true for almost everything.
About the capture of a static piece, you may see that as nice coincidence : the square h3 being visited before and after, for completely different reasons.

of course, all that is said "by the way". The opinion of Miodrag is also most understandable.
 
   
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(31) Posted by Nikola Predrag [Friday, Jul 6, 2012 00:33]

"About the capture of a static piece, you may see that as nice coincidence : the square h3 being visited before and after, for completely different reasons."

That happens in your version and if my superficial retro-analysis is not wrong, there is one unifying reason for those 2 visits.
 
   
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(32) Posted by Jacques Rotenberg [Friday, Jul 6, 2012 00:56]

In the retro, the Rook is in h3 (and not in i3 for example) in order to avoid h3xg4 as a retro move.
In the help play the Knight goes to h3 because, there, he gives mate.
Did I miss something ?
 
   
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(33) Posted by Nikola Predrag [Friday, Jul 6, 2012 01:07]

What was the penultimate white move before the diagram position or what White has played immediately before bR plays from f3 to h3? Maybe I don't see something simple.
 
   
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(34) Posted by Geoff Foster [Friday, Jul 6, 2012 01:31]

A good question! Now I see that White might have played Sg1-h3.
 
   
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(35) Posted by Nikola Predrag [Friday, Jul 6, 2012 01:38]

As I can see, the point is that Black didn't play Rf3-h3 but Rf3xh3, not only to legalize the ep. but to enable Sxh3#.
 
 
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(36) Posted by Jacques Rotenberg [Friday, Jul 6, 2012 01:38]

The Rook captured a white piece of any kind on h3, is it what you mind ? two captures on h3 one before, one after ? why not
 
   
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(37) Posted by Jacques Rotenberg [Friday, Jul 6, 2012 01:44]; edited by Jacques Rotenberg [12-07-06]

Sorry cross posts

ok what you say is more interesting : a kind of extended help play through the mirror
 
   
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(38) Posted by Jacques Rotenberg [Friday, Jul 6, 2012 05:05]; edited by Jacques Rotenberg [12-07-10]

This help play may be shown full on one side of the mirror :

(= 5+8 )
(5+8) h4# 2 sols

1.R×h3+ g4 2.f×g3 e.p.+ f3+ 3.Kf4 Sf2 4.Be5 S×h3‡
1.Se3 f×e3 2.Kf5 Sg3+ 3.Kg5 e×f4+ 4.Kh4 Sf5‡

The second sol is easy to avoid, but it fits well the first : a kind of reciprocal Chumakov, in 1 sol two white guarding pieces are taken, in the other two black blockers are taken. Black sacrifice and model mate in both.
 
   
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(39) Posted by Nikola Predrag [Friday, Jul 6, 2012 15:46]

Wow!
To fulfill the formal definition of 'Chumakov' is easy and the logical unity of sacrifice/selfblock is often trivial and accidental or artificial. For this occasion, I will spare the readers my theoretical complications. :)

Reciprocal black and white 'Chumakov' (white guard of flight compared to black block of flight), beautifully please my hunger for black/white reciprocity of logic elements. I have to think about some details and possibilities, but now I can only repeat - WOW!
 
   
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(40) Posted by Nikola Predrag [Saturday, Jul 7, 2012 00:53]

Active sacrifices are much better than the passive sacrifices, at least because they are a result of help-PLAY. In passive sacrifices only one side plays and the sacrificed piece is placed on the diagram by the author.
Well, in this problem bPf4 is placed by the author, but wPf2 could never capture bPf4 without help by Black. So, captures of both bS and bP are enabled by help-play of bSf5.
wPg2 is actively sacrificed, but wPh3 is not. I don't say that such details are worth additional 2 Pawns, but I give the position with an additional feature.

(= 5+10 )
h#4 2.1...
White has just actively sacrificed a Pawn by a retro-move h2-h3. For the forward play, it guards g4 in one solution but in the other it is(was) a sensless tempo-move, forced by the necessity to legalize the diagram position.

I think that such retro component keeps a minimal continuity of this thread. Also, the mere h# content showing a special double reciprocal 'Chumakov', probably could be realized simplier, avoiding the troubles with ep. capture.
 
   
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