Author: Miguel A. Ballicora
Date: 22:39:15 09/21/01
Go up one level in this thread
On September 22, 2001 at 00:52:06, Robert Hyatt wrote: >On September 22, 2001 at 00:43:03, Robert Hyatt wrote: > >>On September 21, 2001 at 23:45:54, Miguel A. Ballicora wrote: >> >>>On September 21, 2001 at 23:01:29, Robert Hyatt wrote: >>> >>>>On September 21, 2001 at 17:01:35, Miguel A. Ballicora wrote: >>>> >>>>>On September 21, 2001 at 16:45:44, Robert Hyatt wrote: >>>>> >>>>>>On September 21, 2001 at 16:27:01, Gian-Carlo Pascutto wrote: >>>>>> >>>>>>>On September 21, 2001 at 14:57:20, Robert Hyatt wrote: >>>>>>> >>>>>>>>I don't mind that kind of mis-evaluation so much. If anybody wins, white >>>>>>>>wins. What I would not like is to see that kind of evaluation and then lose >>>>>>>>the game... >>>>>>> >>>>>>>The problem is when crafty prefers the 1.8 from this ending over the 1.7 from >>>>>>>another ending that _is_ won for white. >>>>>>> >>>>>>>That'll cost you half a point. >>>>>>> >>>>>>>-- >>>>>>>GCP >>>>>> >>>>>> >>>>>>I don't disagree. But it is just as important to not lose when you can win >>>>>>or draw. The not drawing when you can win is another level of tuning. I need >>>>>>to study the ending because a pawn on the a and c file becomes very hard for >>>>>>a lone king to stop... it might have simply made a mistake and drawn a won >>>>>>position in this case.. I didn't look at it very carefully (yet). >>>>> >>>>>It looks drawn. As you already know, the advantage of the outside passer is that >>>>>you can sacrifice it and the king can go and eat up the opponent pawns on the >>>>>other side. In this case it is impossible (that's the problem here). For >>>>>instance, place the pawns in g6,h5,g4. How can the white king capture them? it >>>>>can't because as soon as you capture g6 black plays h4 and promotes. On the >>>>>other hand, two passers cannot beat a king on the Q side, they need the help of >>>>>the wKing. however, the wK cannot go to the Q side because black promotes. >>>>> >>>>>Regards, >>>>>Miguel >>>> >>>> >>>>I don't believe it is quite that simple. If the pawns are zugged on the >>>>kingside, the two passers on the queenside can easily win. This is the >>>>attraction of "wild 7" on ICC, which is what the "mini game" is all about. >>> >>>I am not sure what you mean by zugged pawns. Anyway, white cannot capture the >>>pawns in any case, so how can white win? two passers, if they are not separated >>>enough, cannot win without king support. >>>The only chance is a race, when white king rush to the Q side to support them >>>letting a black pawn to promote. >>> >>> >>>>In this zug-less position (at present) things aren't so clear, of course, >>>>but >>>>put the black pawns at g5 and h6 and the white pawn at g4, and this turns >>>>into a simple white win... >>> >>>Black plays h5 and it is a draw. I think I did not understand. >>> >>>Regards, >>>Miguel >> >> >>You are assuming that a KQ vs KQPP is a draw? IE after h5, I play gxh5 and I >>promote first. But I play g6xh5 first and you don't promote ;-) I think we are talking about different things. You are setting a position with only h6 and g5? then I have pawn less and has little to do with the game itself. >> >>To understand the rp and bp vs a lone king, requires a bit of thought. But >>once you understand that this is all about zugzwang, you realize that if the >>tempo is mine, and you have _no_ move to make but king moves, you can't stop >>the two pawns. Just visualize the two pawns side by side at a4/c4, with your >>king at b6. It is your move and you have to stop the two pawns. If you play >>Kc5, I play a5 and you can't take the c pawn. If you play Ka5, I play c5 and >>you can't take the a pawn. So you retreat, I advance, and we reach this >>position one rank further up. It's a cute position that once caused a lot >>of interest on ICC until most everyone figured out how to win (white starts >>off with pawns at a2/b2/c2, king at d1. Black has pawns at h7/g7/f7, king >>at e8. White moves and wins every time if he plays right. One wrong move >> > >Part of the above is right. Part is wrong. Too late at night to correct it >now... Depends on how far the pawns are advanced... Of course, but it is not the case of this game! Ok it is late for me too, I better go to sleep... Miguel > >Bob > > > >and black draws or wins. >> >>So calling this a draw or a win or a loss is not so easy for a static eval. >>If black has one "passing" move (wild 7 has white playing a4/c5/a5/c5 until >>the black king stops the pawns, then using the b pawn to gain the necessary >>tempo to win the game) then this doesn't work. In the position I started with >>above, if white has to move, either pawn move loses, as black can then capture >>that pawn and catch the other before it can promote... >> >>That's why I said this was a hard one to evaluate without a lot of searching >>or specific pattern analysis. I don't want to include the specific knowledge >>for the above analysis in Crafty as it would be slower, and it would hardly >>ever be used... >> >>But I do plan to look at the position and see if the eval can be tweaked some >>as it _does_ know that black has a majority. I am probably incorrectly giving >>credit to white for two "distant passers" when there is really only one. And >>black has a distant passer himself that it does know about...
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