Author: Ed Schröder
Date: 00:45:04 01/11/00
Go up one level in this thread
>Posted by Robert Hyatt on January 10, 2000 at 23:38:17:
>
>>>Put black's f7 pawn on g7 and black is suddenly doing lots better.
>>
>>And can save a few bucks as in my case. I think it is doable to write
>>code for this kind of situations only that in the 18 years I am working
>>now on Rebel I haven't seen such a case of a trapped bishop happening.
>>These guys surely know how to debug a chess engine.
>>
>>Ed
>>
>>
>>>bruce
>
>
>There are three issues:
>
>(1) sometimes you simply have to take your lumps and go home. This might be
>considered to be one of those kinds of positions where they are so rare, they
>aren't worth fixing.
Problem: this one can't be solved be search.
>(2) you can also avoid this in a different way, namely the way I do this in
>my eval, by (a) penalizing blocked pawns and (b) rewarding potential pawn
>levers to make sure the position doesn't become so hopelessly blocked as the
>one you saw. CptnBlueBear will murder you with this if you aren't careful, as
>it is _exactly_ what he tries to do. And as a GM, it is very difficult to
>keep him from doing it without accepting a weakness or two that you really
>would prefer not to.
Understood.
Problem-2: Like Crafty Rebel has knowledge on this case only that its current
value (penalty) is in the 0.10 - 0.15 range. For this particular case it should
be at least 1.00 - 2.00 right?
>(3) you can fix this in code. I did it once for Roman. But it was _very_ slow,
>for the good that it provided, and he later agreed that trying to avoid the
>blocked position just because it was blocked, rather than worrying about a
>hopelessly bad bishop, probably was more effective in most cases.
Disadvantage: too often moving into blocked pawns is the only right move
and you need to play the right moves all the time against these guys. One
bad move and you are lost, this game is the ultimate example I would say.
After 21..e5?? the game was over.
>The thing that worries me is that there are _hundreds_ more of these kinds of
>special cases that are left to discover. I have discovered many in my code. I
>am afraid I have only scratched the surface, yet I have over 50,000 blitz games
>vs GM players to go on. :(
Hundreds of these kind of exceptions huh?
I tend to agree, here are two of them:
[d]r4rk1/p1q2ppp/1pn2n2/2p1p3/3PP1b1/P1P2N2/B4PPP/R1BQR1K1 w - - 0 14
[White "Kasparov, Gary"]
[Black "Kramnik, Vladimir"]
14. dxc5! { Natural 14.d5 will be serious positional mistake- bishop on a2
could be closed for a long time.}
I bet most programs (Rebel included play 14.d5). 14.d5 looks okay and for
many good reasons still it's called a serious positional mistake. That hurts!
Case 2:
[d]2rq2k1/4bppp/p1rp4/1p1NpP2/4P3/2PQ4/PP4PP/3R1R1K w - -
Robert Fischer's famous: Ra1!!
I assume almost every program will play f6? here leaving white with
nothing. I wonder if any program will find this fine positional move.
Ed
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