From: Jeroen Tiggelman <Tiggelman <at> CONSUL <dot> NL>
Date: 10 dec 1996
Subject: Re: Evaluation (was Re: Computer Shogi)

>Unpromoted:   Promoted:  Promotion:
>Pawn  = 10    40         30
>Lance = 30    50         20
>Knight= 40    55         15
>Silver= 50    60         10
>Gold  = 60    -


I am thinking about the difference in values of Gold and
the above promoted pieces.

I guess that you rate them so that
 (1) promotion is valued higher for 'weaker' pieces,
       i.e., it is more of an advantage to promote a
      mere Pawn than a Silver, and
(2) It is less severe to lose a promoted Pawn than
      a Silver, since it gives your opponent less.

However, a capture of a promoted piece already
includes "unpromotion", so I am not sure that you
need to take (2)  into account for evaluation of
_your_ position (at an end node in a search tree),
_or_ your opponent's (who just gets a pawn in
hand  or so, which isn't many points anyway.
I may well want to sacrifice a Silver if that gives
me the chance to promote a pawn that won't be
captured.. (especially if that drives the King to
the edge. ;-))

[I also don't think it is consistent with (2), if you do
 want to apply it, that  G and +S would be equal,
 but anyway. ;-)]

>And for each square of mobility the Bishop or
>Rook has, add 1 point.

That's an idea. You might also want to consider
whether you can keep a Rook or Bishop in a
mobile position _within the opponent's camp_,
especially when promoted.

In hand they may have quite some 'mobility',
too... (though you'd probably want to rate it
differently.)

And that a Lance is often more useful in hand
than on its original file.

And that a promoted Rook is most useful in the
opponent's camp, but a promoted Bishop is
excellent for defense, etc. ;-)

BTW, a promoted Bishop is three generals is
about right. I also agree that a Rook is about
two generals. :-)

Jeroen