[Retros] Retros Digest, Vol 146, Issue 2

[Dominique Forlot]

You're right François,

, I made an error in my arithmetic of the length of mat(0,17,7) 

r2qkNnr/ppp1pQpp/8/8/2B2n2/8/PPPP1PPP/RNBbK2R

1.Cg1-f3 Cb8-c6 2.Cf3-e5 Cc6-d4 3.Ce5xd7 Cd4xe2 4.Cd7xf8 Ce2-f4 5.Dd1-h5 Fc8-g4 6.Ff1-c4 Fg4-d1 7.Dh5xf7

mat(0,17,7) 
D(13ply) = 39,69410640 
vitesse 3.053393/ply (and not 2.5117/ply !! :o( ).




Dominique.






> Message du 02/09/16 01:50
> De : retros-request at janko.at
> A : retros at janko.at
> Copie à : 
> Objet : Retros Digest, Vol 146, Issue 2
> 
> On 31/08/16 04:59 AM, Yoav Ben-Zvi wrote:
> > Verification must wait for a full search of all sound SPGs in 6.0.
> 
> Actually, about 5 years ago I did a full search of all sound checkmate 
> PGs up to 6.0 moves. Luckily I found my old files containing those PGs, 
> so I'm able to give examples with maximum geometric length.
> 
> Nicolas's 52.142136 = (38,10,0) in 5.5 moves is optimal, congrats!
> 
> Here are the records from 4.0 to 6.0 moves:
> 
> 4.0 moves: 32.970563 = (16,12,0)
> 1. d4 e5 2. Qd3 Ba3 3. Qxa3 Qg5 4. Qh3 Qxc1#
> second place: 31.970563
> 
> 4.5 moves: 37.526912 = (5,23,0)
> 1. e3 b5 2. Qh5 Bb7 3. g4 Bxh1 4. Bc4 Bb7 5. Bxf7#
> second place: 37.035058
> 
> 5.0 moves: 41.698485 = (12,21,0)
> 1. c4 e5 2. Qc2 Qh4 3. Qxh7 Qxc4 4. Qe4 Ba3 5. Qxb7 Qxc1#
> second place: 41.455844
> 
> 5.5 moves: 52.142136 = (38,10,0)
> 1. e4 h5 2. Qxh5 a5 3. Qxa5 Rxh2 4. Qh5 Ra3 5. Bc4 Rah3 6. Bxf7#
> 1. e4 h5 2. Qxh5 a5 3. Qxa5 Rh3 4. Qh5 Rxa2 5. Bc4 Rha3 6. Bxf7#
> 1. e4 h5 2. Qxh5 a5 3. Qxa5 Rxh2 4. Bc4 Rh8 5. Qh5 Rxa2 6. Bxf7# (Nicolas)
> 1. e4 h5 2. Qxh5 a5 3. Qxa5 Rxh2 4. Qh5 Rxa2 5. Bc4 Ra8 6. Bxf7#
> second place: 51.142136
> 
> 6.0 moves: 56.142136 = (42,10,0)
> 1. a4 e5 2. Ra3 Qh4 3. Rh3 Qxa4 4. Rxh7 Bc5 5. Rh3 Qh4 6. Ra3 Bxf2#
> second place: 55.183766
> 
> It turns out that the records are all unique except for length 5.5! So 
> using the second place lengths, I can formulate the following 
> composition challenge:
> 
> Compose a sound checkmate PG...
> a) in 4.0 moves with total move length > 32.0
> b) in 4.5 moves with total move length > 37.1
> c) in 5.0 moves with total move length > 41.5
> d) in 6.0 moves with total move length > 55.2
> 
> 
> As for Dominique's challenge of the type "checkmate (0,b,c)", some 
> optimal problems are
> 
> 5.5 moves: 33.444893 = (0,11,8)
> 1. Nf3 Nc6 2. Ne5 Nd4 3. Nxd7 Nxe2 4. Ne5 Nf4 5. Bc4 Bh3 6. Bxf7#
> [5 more problems]
> 
> 6.0 moves: 36.273320 = (0,13,8)
> 1. Nc3 Nf6 2. Nd5 Ne4 3. Nxe7 Nxd2 4. Nxc8 Ne4 5. Bg5 Bc5 6. Bxd8 Bxf2#
> [4 more problems]
> 
> but those are not as good as the claimed 39.694106 = (0,17,7) in 6.5 
> moves, even if we compare the average distance per ply, which I compute 
> to be
> 
> (0+17*sqrt(2)+7*sqrt(5))/13 = 3.053393/ply (not 2.5117/ply ?).
> 
> François
> 
>
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