# [Retros] King mated on the 7th/8th rank (computer solved)

Francois Labelle flab at EECS.Berkeley.EDU
Thu Nov 16 13:45:55 EST 2006

Here are the results of a computer analysis of the case "white king with
zero slack moves" which took about 1h. I suspect Mario Richter did the
same with his program.

For each task I show the optimal (#moves,#captures), an example proof game
if I beat the previous record, and the number of proof games with that
number of moves and captures.

White king on ...

a8: (8.0, 1) 1. d4 d5 2. Kd2 Bd7 3. Kc3 Ba4 4. Kb4 b5 5. Ka5 Nc6+ 6. Ka6
Qd7 7. Kb7 Kd8 8. Kxa8 Qc8# (78 PGs)
b8: (8.0, 2) 1. e4 c5 2. Ke2 Qa5 3. Kd3 Qxd2+ 4. Kc4 Qd5+ 5. Kb5 a6+ 6.
Kb6 Ra7 7. Kc7 b5+ 8. Kxb8 Qa8# (9 PGs)
c8: (8.0, 0) 1. e4 e5 2. Ke2 Bb4 3. Kd3 c5 4. Kc4 b5+ 5. Kd5 Bb7+ 6. Kd6
Qf6+ 7. Kc7 Bd5 8. Kc8 Qc6# (72 PGs)
d8: (8.0, 0) 1. f3 e5 2. Kf2 Bb4 3. Ke3 c5 4. Ke4 f5+ 5. Kd5 Kf7 6. Kd6
Qf6+ 7. Kc7 Qc6+ 8. Kd8 Ba5# (25 PGs)
e8: (8.0, 0) 1. e3 d5 2. Ke2 Kd7 3. Kf3 Kc6 4. Kf4 Nd7 5. Kf5 f6 6. Ke6
Nb6+ 7. Kf7 Qd6 8. Ke8 Be6# (6 PGs)
f8: (8.0, 1) 1. e4 e5 2. Ke2 Bb4 3. Kf3 Ke7 4. Kg4 f5+ 5. Kxf5 h5 6. Kg6
Kd6 7. Kf7 Qg5 8. Kf8 Nh6# (31 PGs)
g8: (8.0, 0) 1. f4 h5 2. Kf2 h4 3. Kf3 h3 4. Kg4 f5+ 5. Kg5 Rh5+ 6. Kg6
Nh6 7. Kh7 Ng4+ 8. Kg8 Nf6# (1 PG!)
h8: (8.0, 0) 1. f4 h5 2. Kf2 h4 3. Kf3 h3 4. Kg4 f5+ 5. Kg5 Rh5+ 6. Kg6
Rg5+ 7. Kh7 Nf6+ 8. Kh8 Rh5# (2 PGs)

a7: (7.0, 1) 1. d3 b6 2. Kd2 Bb7 3. Kc3 Bd5 4. Kb4 Nc6+ 5. Kb5 Rb8 6. Ka6
Nb4+ 7. Kxa7 Rb7# (4 PGs)
b7: (7.0, 0) (Hirokaz Onoda) (318 PGs)
c7: (7.0, 0) 1. e4 e5 2. Ke2 Bb4 3. Kd3 c5 4. Kc4 Nc6 5. Kd5 Rb8 6. Kd6
Qe7+ 7. Kc7 d5# (291 PGs)
d7: (8.0+, ?) ???
e7: (7.0, 0) 1. e4 e5 2. Ke2 Bb4 3. Kd3 c5 4. Kc4 Qa5 5. Kd5 Nf6+ 6. Kd6
O-O 7. Ke7 c4# (9 PGs)
f7: (7.0, 0) (Mario Richter) (44 PGs)
g7: (7.0, 0) (Hirokaz Onoda) (309 PGs)
h7: (7.0, 1) 1. e4 e5 2. Ke2 Bd6 3. Kf3 Qf6+ 4. Kg4 Ne7 5. Kh5 g6+ 6. Kh6
Rg8 7. Kxh7 Qh8# (52 PGs)

Now the case "black king with zero slack moves" which took about 10h.

Black king on ...

a1: (8.5, 0) 1. a4 e6 2. Ra3 Ke7 3. Rf3 Kd6 4. e3 Kc5 5. Qe2 Kb4 6. c3+
Kb3 7. d3 Ka2 8. b4+ Ka1 9. Qb2# (18 PGs)
b1: (8.5, 0) 1. d4 e6 2. Nd2 Ke7 3. Nb3 Kd6 4. Bf4+ Kd5 5. Nc1 Kc4 6. b3+
Kc3 7. a4 Kb2 8. Ra3 Kb1 9. Nd3# (2 PGs)
c1: (8.5, 0) 1. d4 d5 2. Bh6 Kd7 3. e3 Ke6 4. Bb5 Kf5 5. c4 Ke4 6. Qa4 Kd3
7. Qb4 Kc2 8. Be8 Kc1 9. Na3# (549 PGs)
d1: (8.5, 0) 1. Nc3 d6 2. Nd5 Kd7 3. c3 Kc6 4. Qa4+ Kc5 5. Qe8 Kc4 6. a3
Kb3 7. f3 Kc2 8. Kf2 Kd1 9. Ne3# (434 PGs)
e1: (8.5, 0) 1. d4 f5 2. Qd2 Kf7 3. Kd1 Ke6 4. Qh6+ Kd5 5. Bg5 Ke4 6. f4
Ke3 7. Kc1 Kf2 8. Nh3+ Ke1 9. Bh4# (63 PGs)
f1: (8.5, 0) 1. e4 d5 2. Qh5 Kd7 3. Bb5+ Kd6 4. d3 Kc5 5. Bh6 Kd4 6. f4
Ke3 7. Kd1 Kf2 8. Be8 Kf1 9. Qe2# (198 PGs)
g1: (8.5, 0) 1. e4 e5 2. Be2 Ke7 3. Bh5 Kf6 4. g4 Kg5 5. h4+ Kf4 6. Ne2+
Kf3 7. Rh3+ Kg2 8. Nf4+ Kg1 9. Ke2# (2 PGs)
h1: (8.5, 0) 1. h4 f5 2. Rh3 Kf7 3. Ra3 Kg6 4. d3 Kh5 5. Qd2 Kg4 6. f3+
Kg3 7. e3 Kh2 8. g3+ Kh1 9. Qg2# (167 PGs)

a2: (7.5, 1) 1. c3 f6 2. Qa4 Kf7 3. Qxa7 Ke6 4. a4 Kd5 5. Qa5+ Kc4 6. Na3+
Kb3 7. Rb1 Ka2 8. Qd5# (68 PGs)
b2: (7.5, 0) 1. b4 d6 2. Bb2 Kd7 3. Be5 Kc6 4. Bf4 Kb5 5. e3+ Ka4 6. Nc3+
Ka3 7. Bb5 Kb2 8. Qc1# (420 PGs)
c2: (7.5, 0) 1. e4 f6 2. Be2 Kf7 3. Bh5+ Ke6 4. Be8 Ke5 5. Qh5+ Kd4 6. c3+
Kd3 7. Qd5+ Kc2 8. Na3# (800 PGs)
d2: (7.5, 0) 1. d4 d5 2. Bg5 Kd7 3. f4 Ke6 4. Kf2 Kf5 5. Kg3 Ke4 6. Nc3+
Ke3 7. Qb1 Kd2 8. f5# (5 PGs)
e2: (7.5, 0) 1. e4 f6 2. Bb5 Kf7 3. Qh5+ Ke6 4. Qe8 Ke5 5. c4 Kd4 6. Nf3+
Kd3 7. O-O Ke2 8. c5# (24 PGs)
f2: (7.5, 0) 1. f4 d6 2. f5 Kd7 3. f6 Ke6 4. d4 Kf5 5. Bh6 Kg4 6. h3+ Kg3
7. Kd2 Kf2 8. Qe1# (88 PGs)
g2: (7.5, 0) 1. e3 d6 2. Ne2 Kd7 3. Nec3 Ke6 4. Bc4+ Kf5 5. Ke2 Kg4 6. g3
Kh3 7. Be6+ Kg2 8. Qf1# (270 PGs)
h2: (7.5, 1) 1. g3 d6 2. Bg2 Kd7 3. Kf1 Ke6 4. Bd5+ Kf5 5. Nf3 Kg4 6. Rg1
Kh3 7. Ng5+ Kxh2 8. Rh1# (224 PGs)

I'm currently doing a special search for the missing PG (white king on d7
mated in 8.0 moves). Will anyone find such a PG before the computer?

Francois