[Retros] At-home initial array challenge

Francois Labelle flab at EECS.Berkeley.EDU
Wed Mar 30 19:56:11 EST 2005

François Perruchaud wrote:

> Here are all the PGs mentioned in previous messages up to 8.5 moves.

> Is the list complete ?

The list is complete, according to my computer. I tested every possible
diagram with Euclide (Mario Richter's technique, to try it). Now I
understand Mario's viewpoint better. Natch and Euclide spend a long time
on problems which can be dismissed as impossible instantly by counting the
number of captures (Popeye doesn't have this problem because its engine
seems to be based on such counting). So I eliminated the impossible <=0
non-captures problems myself. Maybe it would have been even better to
dispatch the 1 non-capture cases to Popeye instead of Euclide.

> Note that I later gave two PGs with 4 non-captures. 4 is really BIG ;-)

By contrast, here are some fairy problems with very few non-captures that
I found:

Nightrider Chess, 0 non-captures
r1bqk3/ppp1ppp1/8/8/8/8/PPPPPPPP/RNBQKBNR in 5.5
r2qk2r/ppp1ppp1/8/8/8/8/PPPPPPPP/RNBQKBNR in 5.5
rn2kb1r/2pp1ppp/8/8/8/8/PPPPPPPP/RNBQKBNR in 5.5
They appear to be plentiful. I found many more in >=6.0 (x+16 and 16+x).

Circe, 1 non-capture, C+ Popeye (inspired by Juha Saukkola's idea)
r1bqkb2/p1p1p3/8/8/8/8/PPPPPPPP/RNBQKBNR in 9.0
r3k1n1/p1p2pp1/8/8/8/8/PPPPPPPP/RNBQKBNR in 10.0


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