Joost Brugh wrote on Fri, Mar 31, 2006 03:44 PM UTC:
In Shogi, it is illegal to drop a Pawn to give checkmate. In Zillions, this
is hard to program, because you have to detect checkmate 'by hand'. And
indeed, there is still a possibility to give checkmate by dropping a Pawn
in the Shogi ZRF. If you drop a Pawn on a position which is defended by a
pinned defender, you can give checkmate. This is an easy error to make,
because Zillions doesn't think you should use a checkmate condition for
something else than ending the game (though Shogi is included in Zillions
itself). Stranger is that the Shogi Variant program (there is a link from
this site to that program), that error is also made. It is strange that
the program is able to detect checkmate (It says: Game over), but it
didn't detect checkmate to render the Pawn drop illegal. So I wondered
what the exact rule is: 'A Pawn cannot be dropped to give checkmate' or
'A Pawn dropped to give check is only legal if dropped on an attacked
position or if the King has a flight square' (The latter case would
legalize a Pawn drop mate on a position attacked by a pinned defender.
