[Retros] FW: FW: distance-PG-

Yoav Ben-Zvi yoavbz97 at gmail.com
Sat Sep 10 15:39:06 EDT 2016


Thanks again to François. The discrepancy noted in the minimal average is my
mistake. The correct figure (1.224) might well be the over-all optimum but
this is not certain. The figure achieved for the maximal average (2.75)
looks easy to beat but I found it very difficult and finally found the

Natch 3.0.beta      Copyright (C) 1997,98,99,2001-2005,2016 Pascal Wassong 



19 single moves.               15 + 11


The resolution begins at Sat Sep 10 19:37:36 2016


Solution 1 (position 1)

1.Pe2-e4   Pd7-d5   2.Pe4xd5   Ke8-d7   3.Qd1-g4   Kd7-d6   

4.Qg4-b4   Pc7-c5   5.Pd5xc6   Kd6-e5   6.Pc6xb7   Qd8-d4   

7.Pb7xa8=R Bc8-a6   8.Ra8xa7   Ba6xf1   9.Ra7-a3   Sb8-a6   



The resolution ends at Sat Sep 10 19:37:36 2016

Solution found: 1

Position analysed: 1

Resolution time: 0.03 s


This has 28+16*SQRT2+SQRT5=52.863 / 19 = 2.78 


The challenge remains to improve on these results.




From: Retros [mailto:retros-bounces at janko.at] On Behalf Of Francois Labelle
Sent: Friday, September 09, 2016 10:08 PM
To: retros at janko.at
Subject: Re: [Retros] FW: distance-PG-


Yoav Ben-Zvi wrote:

To get something new without greater complexity I suggest to exchange the
mate condition with e.p. capture: 

Shortest sound SPG with e.p. capture that has a)Maximal, b)Minimal distance 

My intended solutions are 4.5 moves with distance 12+6*SQRT2=20.485
(/9=2.276) for a) and 8+4*SQRT2=13.657 (/9=1.517) for b).

It should be possible to verify (or cook) with the files generated by

Congratulations, these are the maximal/minimal distances in 4.5 moves. The
solutions are unique, so you must have found these:
20.485281 = (12,6,0): 1. e4 d5 2. exd5 Kd7 3. Qg4+ Kd6 4. Qb4+ c5 5. dxc6+
13.656854 = (8,4,0): 1. b4 e6 2. Ba3 Ke7 3. Qc1 Kd6 4. b5+ c5 5. bxc6+

An open-ended version:

Sound SPG with e.p. capture that has a)Maximal b)Minimal average distance
per move. My preliminary candidate for a) has 5.0 moves with average
distance of 2.755 and for b) my candidate has 5.0 moves with average of

Below are the maximal/minimal distances in 5.0 moves. The solutions are

27.556349 = (12,11,0): 1. d4 e5 2. Bh6 exd4 3. Kd2 Qg5+ 4. Kd3 Qb5+ 5. c4
12.242641 = (8,3,0): 1. f3 h6 2. Kf2 h5 3. Kg3 h4+ 4. Kh3 d6+ 5. g4 hxg3+

Did you really find something shorter than my computer? (1.124 vs 1.224)

That's everything I have, for e.p. I only have PGs up to 5.0 moves.


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