[Retros] total homebase mate

[andrew buchanan]

For Ka1, a similar solution works:

SPG 9.0 C+
rnbqkbnr/1ppppppp/8/8/3P1Q2/4B3/1PP1PPPP/KR3BNR w KQkq - id 18;

Note the positions of the White dP, B & Q are uniquely determined by
the requirement to ensure mate.

The set of candidate squares where the wK might be homebasely mated is
revised:

1qq5/rbq3b1/KqnKbK1K/K1bq1bqr/rb1q2bK/K2q3K/r2q3r/r2q3r w - -
key: 
Bl units show checkmating piece for that square.
wK indicates that multiple Bl units might mate on that square (perhaps
by double check mate?)

This is derived from the following steps:
(1) square must not be adjacent to bK
(2) square must be checkable by Black officer
(3) a8 => bBc8 is missing => b7 not attacked, but no Wh unit ok for b7.
(4) h7 => no protection for bRh8 possible

cheers,
andrew.

--- Nicolas.Dupont at math.univ-lille1.fr wrote:


> > Here is another homebase mate, which I think is the shortest yet.

> >

> > SPG 7.0 C+

> > rnbqkbnr/ppppppp1/8/8/4P3/3B4/PPPPNPP1/RNB3RK w KQkq - id 14;

> 

> Good trick, Andrew ! Are you able to find a similar one for Ka1 ?

> 

> > As far as approaches are concerned, my over-riding concern in this

> sort

> > of task is to minimize the number of moves.

> 

> I agree. But shaking the old classical move number approach isn't

> without

> interest.

> 

> It might be appealing to find a case where the 2 records are

> different.

> I tried Kh3 with only Pd7 missed for black, without success.

> 

> Cheers,

> 

> Nicolas.

>