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Old October 6th 09, 09:23 PM posted to rec.games.chess.misc,alt.chess,rec.games.chess.computer,alt.math.recreational
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Default Source for Eight Officers Problem?: Addendum

Simon Krahnke wrote:
* William Elliot (09:55) schrieb:

An improvement in which both rooks are attacked by the queen.

R r r r r r r r
R B Q B b n Q r
R b B b n Q N r
R B b B Q K n r
R Q Q Q B N K r
R Q Q Q Q Q Q r
R Q Q Q N b B r
R R R R R R R R


Same problem, how does that queen on c3 attack c7?


Best I have been able to do manually on paper for the original stated
problem is to leave one square not attacked. In this notation it is.

R r r r r r r r
R K K K N Q B r
R K K K n Q b r
R K K K Q Q Q r
R Q Q Q Q Q Q r
R n N n Q Q Q r
R B b B b Q . r
R R R R R R R R

Subject to typos. Pieces are

R a1
r h8
n c5
N d5
B c3
b d3
K c6
Q f4

R, r placed to reduce to a 6x6 board
K, Q placed to maximise their coverage
symmetry breaking seems to help use N, n.

I'd be interested in the proof that it is impossible to solve without
using two bishops the same colour.

Regards,
Martin Brown

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