[Retros] FW: FW: Distance-PG

[Yoav Ben-Zvi]

I should have made it clear that the claim of candidate task for my problem
depends on the length of the SPG exceeding a limit of 11.0 (or maybe a
slightly lower limit). 

The profound analysis by Nicolas (copied below) investigates the maximal
average distance per move for any sound mate SPG. I suggest  a secondary
challenge by adding  the condition of mate by Black. The current candidate
is the computer generated SPG in 6.0 provided by François:
6.0 moves: 56.142136 = (42,10,0) / 12 = 4.6785
1. a4 e5 2. Ra3 Qh4 3. Rh3 Qxa4 4. Rxh7 Bc5 5. Rh3 Qh4 6. Ra3 Bxf2# 
Perhaps this can also be beaten.

Yoav 

-----Original Message-----
From: Retros [mailto:retros-bounces at janko.at] On Behalf Of Nicolas Dupont
Sent: Saturday, September 03, 2016 6:01 PM
To: retros at janko.at
Subject: Re: [Retros] FW: FW: FW: Distance-PG

> The Mate SPG in 11.5 shown below achieves an average above 3.91

When the only constraint is to reach a checkmate position, the actual Max
for move-length average is 4,74 (list of 5.5 games provided by François). I
thought possible to overstep 5 via the game:

1. Pe2-e4   Ph7-h5     2. Dd1xh5   Pa7-a5     3. Dh5xa5   Th8-h3
4. Da5-h5   Ta8xa2     5. Ff1-c4   Ta2-a8     6. Ta1xa8   Th3-a3
7. Fc4xf7#

But it is surprisingly cooked because of the alternative:

1. Pe2-e4   Pa7-a6     2. Ff1xa6   Ph7-h5     3. Fa6-c4   Ta8xa2
4. Ta1xa2   Th8-h6     5. Ta2-a8   Th6-a6     6. Dd1xh5   Ta6-a3
7. Fc4xf7#

I'm nevertheless able to break 4,74 (but not 5), via the following game:

1. Pe2-e4   Ph7-h5     2. Dd1xh5   Pa7-a5     3. Dh5xa5   Th8-h3
4. Da5-h5   Ta8xa2     5. Ff1-c4   Ta2-a8     6. Ta1-a6   Th3-a3
7. Ta6-h6   Ta3-a7     8. Fc4xf7#

It is a #(60,10,0) in 7.5 with move-length average around 4,94.  
Breaking the emblematic 5 barrier is thus still open.


> Message du 04/09/16 07:42
> De : retros-request at janko.at
> A : retros at janko.at
> Copie à : 
> Objet : Retros Digest, Vol 146, Issue 8
> 
> 
> Thanks to François for clearing up many of the issues. There have been a
> number of suggestions for follow-up questions but I continue to be
> interested in the idea (raised by Dominique) of maximizing the average
> distance per move in a sound SPG (with or without conditions such as
> checkmate or no-capture). This is true despite (or possibly because) of
the
> fact that the computer will not settle this issue in the near future. The
> Mate SPG in 11.5 shown below achieves an average above 3.91
> (19+36*SQRT2+9*SQRT5) by extending the scheme proposed by Dominique. I
> suspect it is possible to surpass 4.0.
> 
> Natch 3.0.beta Copyright (C) 1997,98,99,2001-2005,2016 Pascal Wassong
> 
> +---+---+---+---+---+---+---+---+
> | | . | | . |*K | . |*S |*R |
> +---+---+---+---+---+---+---+---+
> |*P |*P |*P | | . | Q |*P |*P |
> +---+---+---+---+---+---+---+---+
> | B | . | | . | | . | |*Q |
> +---+---+---+---+---+---+---+---+
> | . | | . | | S | | . | |
> +---+---+---+---+---+---+---+---+
> | | . | | . | | . | | B |
> +---+---+---+---+---+---+---+---+
> |*B | |*S | | . | | . | |
> +---+---+---+---+---+---+---+---+
> | P | P | P |*R | | P | P | P |
> +---+---+---+---+---+---+---+---+
> | R | | . |*B | . | R | K | |
> +---+---+---+---+---+---+---+---+
> 4k1sr/ppp2Qpp/B6q/4S3/7B/b1s5/PPPr1PPP/R2b1RK1
> 23 single moves. 13 + 13
> 
> The resolution begins at Fri Sep 02 22:01:50 2016
> 
> Solution 1 (position 2)
> 1.Sg1-f3 Sb8-c6 2.Sf3-e5 Sc6-d4 3.Se5xPd7 Sd4xPe2 
> 4.Sd7-e5 Se2-c3 5.Qd1-h5 Bc8-g4 6.Bf1-a6 Bg4-d1 
> 7. O-O Qd8xPd2 8.Sb1-a3 Qd2-h6 9.Bc1-g5 Ra8-d8 
> 10.Bg5xPe7 Rd8-d2 11.Be7-h4 Bf8xSa3 12.Qh5xPf7 
> 
> The resolution ends at Fri Sep 02 22:01:50 2016
> Solution found: 1
> Positions analysed: 3
> Resolution time: 0.23 s 
> 
> In the above notation uncaptured pieces are identified in order to make it
> easy to play backward from the diagram. This is a task problem without
much
> artistic merit still there are some points of interest such as the unique
> destination of 4...Se2-c3, the requirement for a "Turton Voidance" of g4
by
> WQ for BB that invalidates 5.Qd1-f3 and the requirement for "Bristol"
> clearance of g5 by BQ for WB that invalidates 8...BRa8-d8.
> 
> Yoav 
>

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