[Retros] 8th row mates by knight promotion

[Mario Richter]

Hello Olli,


>> The groups that I improved are:

>> b (earlier record 8.0), c (8.0), g (8.5), bxa (7.0),

>> axb (8.0), cxb (7.0), dxc (8.0), dxe (9.0), fxe (9.0),

>> fxg (8.0) and hxg (8.5).


Great work! And still at least in some cases not the minimum:

Pa7xb8=N  13 plies (former record: Olli 15)
1Nbq1bnr/2pkpQpp/p2p4/8/8/8/PP1PPPPP/RNB1KBNR
1. Pc2-c4   Pb7-b6     2. Qd1-b3   Pb6-b5     3. Pc4xb5   Pa7-a6    
4. Pb5-b6   Ra8-a7     5. Pb6xa7   Pd7-d6     6. Qb3xf7   Ke8-d7    
7. Pa7xb8=N 


Pd7xc8=N  13 plies (Olli 14)
rnN2bnr/ppp2ppp/2qk4/5Q2/4p3/8/PP1PPPPP/RNB1KBNR
 1. Pc2-c4   Pe7-e5     2. Pc4-c5   Qd8-f6     3. Pc5-c6   Ke8-e7    
 4. Pc6xd7   Qf6-c6     5. Qd1-c2   Ke7-d6     6. Qc2-f5   Pe5-e4    
 7. Pd7xc8=N 


Pf7xg8=N  13 plies (Olli 14)
rnbq1bN1/ppppk2p/6Q1/4ppp1/8/8/PPPP1PPP/RNB1KBNR
 1. Pe2-e4   Pf7-f5     2. Pe4-e5   Ng8-f6     3. Pe5xf6   Pe7-e5    
 4. Pf6-f7   Ke8-e7     5. Qd1-h5   Pg7-g5     6. Qh5-g6   Rh8-g8    
 7. Pf7xg8=N 


Furthermore: 

Pf7-f8=N  13 plies (Andrew 14)
rnbqrN2/ppppk1Qp/3b4/4pp2/8/8/PPPP1PPP/RNB1KBNR
 1. Pe2-e4   Pf7-f5     2. Pe4-e5   Ng8-f6     3. Pe5xf6   Pe7-e5    
 4. Qd1-g4   Bf8-d6     5. Pf6-f7   Ke8-e7     6. Qg4xg7   Rh8-e8    
 7. Pf7-f8=N 


And as one could expect, many of the bishop cases are not 
minimal too:

Pb7-b8=B 13 plies (Andrew 18)
rBbq1bnr/Q1kp1ppp/n1p1p3/8/8/8/PP1PPPPP/RNB1KBNR
 1. Pc2-c4   Pe7-e6     2. Pc4-c5   Ke8-e7     3. Pc5-c6   Ke7-d6    
 4. Pc6xb7   Pc7-c6     5. Qd1-a4   Kd6-c7     6. Qa4xa7   Nb8-a6    
 7. Pb7-b8=B 
(This would also improve the Q and R case - but I don't know
 if here and in the Pg7-g8=B case discovered and/or double-check
 are allowed ...)

Pg7-g8=B 13 plies (Hirokaz 14)
rnb1qbBr/pppp1k1Q/5p1p/8/8/8/PPP1PPPP/RNB1KBNR
 1. Pd2-d4   Pe7-e5     2. Pd4xe5   Ng8-f6     3. Pe5xf6   Ph7-h6    
 4. Pf6xg7   Pf7-f6     5. Qd1-d3   Ke8-f7     6. Qd3-h7   Qd8-e8    
 7. Pg7-g8=B 


Pb7xa8=B 13 plies (Andrew 16)
Bn3bnr/p1pqpppp/2kp2b1/8/1Q6/8/PP1PPPPP/RNB1KBNR
 1. Pc2-c4   Pd7-d6     2. Pc4-c5   Bc8-f5     3. Pc5-c6   Bf5-g6    
 4. Pc6xb7   Ke8-d7     5. Qd1-b3   Kd7-c6     6. Qb3-b4   Qd8-d7    
 7. Pb7xa8=B 


Pc7xd8 13 plies (Hirokaz 14)
r1bB1bnr/pp2pppp/1k1p4/2p5/Q7/8/PPP1PPPP/RNB1KBNR
 1. Pd2-d4   Pc7-c5     2. Pd4-d5   Nb8-c6     3. Pd5xc6   Pd7-d6    
 4. Pc6-c7   Ke8-d7     5. Qd1-d4   Kd7-c6     6. Qd4-a4   Kc6-b6    
 7. Pc7xd8=B 


Pg7xh8=B 13 plies (Andrew 14)
rnb4B/ppp1qp1p/5k2/8/6Q1/b7/PPP1PPPP/RNB1KBNR
 1. Pd2-d4   Pe7-e5     2. Pd4xe5   Ng8-f6     3. Pe5xf6   Bf8-a3    
 4. Pf6xg7   Ke8-e7     5. Qd1xd7   Ke7-f6     6. Qd7-g4   Qd8-e7    
 7. Pg7xh8=B 


Happy New Year!

  mario