Author: Robert Hyatt
Date: 19:48:29 10/16/02
Go up one level in this thread
On October 16, 2002 at 15:04:19, Sergei S. Markoff wrote:
>Hello Robert!
>
>Sorry for my penetration, but because I'm trying to be well in computer chess I
>must know all about Crafty from line #1 to the end (:
>
>========= Crafty 19.0, evaluate.c, from line #133 ===========
[block 1]
wfile > bfile+1 if it is btm
wfile+1 > bfile+1 if it is wtm
> if (wfile+wtm > bfile+1) {
> if (wfile < FirstOne8Bit(tree->pawn_score.allb))
> pscore+=WON_KP_ENDING;
> }
[block 2]
wfile < bfile-1 if it is btm
wfile-1 < bfile-1 if it is wtm
> else if (wfile-wtm < bfile-1) {
> if (wfile > LastOne8Bit(tree->pawn_score.allb))
> pscore+=WON_KP_ENDING;
> }
[block 3]
bfile > wfile+1 if it is btm
bfile > wfile if it is wtm
Note that the test above is the same as the test in block 1 above.
> if (bfile > wfile+1-wtm) { // must be "(bfile > wfile+1-!wtm)" ??
> if (bfile < FirstOne8Bit(tree->pawn_score.allw))
> pscore+=-WON_KP_ENDING;
> }
[block 4]
bfile <wfile if wtm
bfile < wfile-1 if btm
Nte that this is the same as block 2, mathematically.
> else if (bfile < wfile-1+wtm) { // must be "(bfile < wfile-1+!wtm)" ??
> if (bfile > LastOne8Bit(tree->pawn_score.allw))
> pscore+=-WON_KP_ENDING;
> }
Note that the two inequalities:
a < b
and a+1 < b+1 are identical, mathematically, and that I use it above to avoid
doing the extra work (!wtm is really bad, by the way, my ChangeSide(wtm) macro
is far faster).
>=============================================================
>
>Strange assymmetric evaluation for black/white. See my comments in listed
>fragment.
>
>Sincerelly yours,
>Sergei
>
>P.S. Why Crafty is still not using (ext-d) futility pruning / razoring?
I didn't like them the last time I tried them. I am trying to find time to
evaluate code that
was recently sent to me, but time is not easy to come by right now.
>P.P.S. I'm not supports your optimism about new extension limitation scheme, my
>test shows that old scheme is better... But I may be wrong.
It isn't clear to me yet, but I like the more consistent time between each
successive iteration,
all else being equal. I'm trying to slow down the extensions, not kick them
into high gear,
for real games rather than test p[ositions...
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