[Retros] HAP webpage updated

Francois Labelle flab at EECS.Berkeley.EDU
Tue Dec 4 04:02:11 EST 2007

On Mon, 3 Dec 2007, Mario Richter wrote:

> Now, is the same possible (like in StenoChess)

> for the 20 first black moves?

Sure. Here are shortest problems for 19 of the 20 first black moves. If
anyone is wondering, in case of a tie it happens that I report the first
problem in lexicographic order (strcmp for programmers).

a6: 1.P P 2.HxP P 3.PxP HxP 4.HxP
a5: 1.P P 2.A P 3.AxP AxA 4.HxA
b6: 1.P P 2.H H 3.HxA HxH
b5: 1.A P 2.P H 3.HxP HxA
c6: 1.P P 2.H H 3.HxA HxP+ 4.H
c5: 1.P P 2.H H 3.HxA PxP
d6: 1.P P 2.H HxP 3.H+
d5: 1.A P 2.AxP HxA
e6: 1.P P 2.H A 3.HxA HxP
e5: 1.A P 2.AxP A 3.AxA
f6: 1.P P 2.H A 3.HxP AxP 4.H#
f5: 1.P P 2.H PxP 3.HxH+
g6: 1.P P 2.H H 3.HxP HxH 4.HxA+
g5: 1.A P 2.P H 3.HxP HxA+
h6: 1.P P 2.HxP P 3.H PxH 4.H#
h5: 1.P P 2.HxP A 3.HxA AxP
Na6: 1.P A 2.HxA P 3.PxP HxP
Nc6: 1.P A 2.H AxP 3.H AxH+
Nf6: 1.P A 2.H P 3.HxA HxP
Nh6: (requires at least 8 plies)

Also there are 88 problems in 4.5 moves ending with a promotion. Here's a
fun quadruple:

1.P P 2.P H 3.PxH H 4.PxP HxA 5.P=A
" " " " 5.P=H
" " " " 5.P=A+
" " " " 5.P=H#

Solutions to the 15 "White's first move" problems that I posted a few days

1.a4 b5 2.Ra3 Ba6 3.Rb3 bxa4 4.Rxb8
1.b3 e6 2.Ba3 Qf6 3.Bxf8 Qxa1
1.b4 Nf6 2.Bb2 e6 3.Bxf6 Bxb4
1.c3 d5 2.Qb3 Bf5 3.Qxd5 Bxb1 4.Qxd8+
1.c4 a5 2.Nc3 a4 3.Nxa4 Rxa4 4.Qxa4
1.d3 g5 2.Nc3 Bg7 3.Bxg5 Bxc3+
1.d4 Nc6 2.Qd3 Nxd4 3.Qf3 Nxf3+
1.e3 b5 2.Nf3 Bb7 3.Bxb5 Bxf3
1.e4 f5 2.Qf3 fxe4 3.Qxf8+
1.f3 e5 2.Kf2 Qh4+ 3.Ke3 Qd4#
1.f4 e5 2.Nf3 Qh4+ 3.Nxh4 exf4
1.g3 d5 2.Bh3 Qd6 3.Bxc8 Qxg3 4.Bd7+
1.g4 d6 2.Bg2 Bxg4 3.Bc6+
1.h3 d5 2.Nc3 Bxh3 3.Nxd5 Qxd5 4.gxh3
1.h4 g5 2.Rh3 Bh6 3.Rg3 gxh4 4.Rxg8+
1.Na3 e5 2.d4 exd4 3.Qxd4 Bxa3
1.Nc3 d5 2.Nxd5 Qxd5
1.Nf3 e5 2.Nxe5 Nc6 3.Nxc6
1.Nh3 e5 2.f4 Qf6 3.fxe5 Qxf1+ 4.Rxf1

Congratulations to Joost for finding an optimal game for a3! He's a bit
lucky... I was calculating ply 8 (which should take only 2.5 days) but
there was a power failure so I had to restart it, and then I unplugged my
computer by mistake, so I had to restart it a second time. I'll write a
report about the ply 8 computation when it's done.

About my infinite chess problem, it clashes with the Codex for Chess
Composition, so the fix is to add the stipulation "No Codex", as done by
Richard Stanley & Andrew Buchanan for their infinite A-to-B problem:

(an explanation appears in the 3rd paragraph.)

::Sigh:: I wish the Codex would simply clarify the effect of the laws of

chess when it's not obvious (like in retractors), and never contradict the
laws of chess like it does for helpgames.

For example, there are 2439530234167 possible ways to play the first 9
plies in chess, but the corresponding question "how many ways are there to
play the first 9 plies in chess?" is a "mathematical chess composition",
so you end up with a number that isn't the answer to the question that
asks for that number, because of the Codex.


More information about the Retros mailing list