[Retros] N2A: 8 queens + 1 rook

[Alain BROBECKER]

Dear retro fans,



Computer found the following one with one rook, 8 queens

and 7 squares controlled twice, but solution is on the

board's edge, which might seem less nice (?).

With 9 queens we can go up to 12 squares controlled twice,

but if we want BK inside the board we must decrease to 7

squares controlled twice as in previous problem.



Will continue to look for two rooks etc, but the computing

becomes much slower with those replacements, and nothing

was found after 1 day of computing.



Best regards, Alain




N2Ai) Alain Brobecker & Computer

Original 2011/04/07

3R4/1Q6/6Q1/2Q5/Q7/4Q2Q/5Q2/Q7

9+0: Add 2 units.



Solution:

Squares controlled twice are a5, b8, c4, c7, e2, g8 and h2,
all other squares are controlled three times or more.

BK on c8 or e8 with capture and promotion to rook is not
possible since c8 and e8 are controlled 4 times.

The only square which is controlled only twice and
allows enough room for WK to parry the second check is
 g8,
so +BKg8 +WKe8.

Alain Brobecker (abrobecker at yahoo.com) |_  _  _ |_
http://abrobecker.free.fr/             |_)(_|(_|| ) of  Arm's Tech