Author: Oliver Roese
Date: 23:35:19 06/13/00
Go up one level in this thread
On June 13, 2000 at 17:36:48, blass uri wrote: >On June 13, 2000 at 16:40:54, blass uri wrote: > >>On June 13, 2000 at 15:45:28, Christophe Theron wrote: >> >>>On June 13, 2000 at 08:36:24, Oliver Roese wrote: >>> >>>>On June 12, 2000 at 05:46:59, Rémi Coulom wrote: >>>> >>>>>On June 10, 2000 at 13:44:35, blass uri wrote: >>>>> >>>>>>On June 10, 2000 at 11:54:17, Ed Schröder wrote: >>>>>> >>>>>[...] >>>>>>> >>>>>>>Maybe the opposite is true. It depends per program how the programmer >>>>>>>looks at things. For this position I would say that having 2 outside >>>>>>>passers usually is a great advantage and as such is rewarded by a chess >>>>>>>program. If so then this position is an exception to the rule. And the >>>>>>>end-game is full of exceptions much more than the mid-game. >>>>>>> >>>>>>>Ed >>>>>> >>>>>>Having 2 outsides passed pawns is an advantage but having 2 advanced passed pawn >>>>>>is also an advantage. >>>>>> >>>>>>The problem is to know which advantage is bigger. >>>>>> >>>>>>I agree that it is not a simple problem and I understand the fact that >>>>>>programmers prefer to waste more time about other problems. >>>>>> >>>>>>I still believe that it is possible to see it at evaluation time by an array >>>>>>64*64*64 of distance to promotion. >>>>> >>>>>You are perfectly right about this idea. I do it in TCB. I have a table for >>>>>distance to promotion for KPK and PPK. In fact, it is not really a table of >>>>>distance to promotion, but a table that gives the maximum number of "not a King >>>>>move by the opponent" before the pawn is promoted. I call it "extended square of >>>>>the King". It is not in the latest version of TCB. I will make it available in >>>>>the next version. If programmers are interested in the code to generate the >>>>>table, I will send it to them. >>>>> >>>>>PPK is nice, but KPK is probably much more useful. TCB can solve WAC #100 in 25 >>>>>seconds or so on a celeron 400 thanks to it. It saves 3 or 4 plies as compared >>>>>to the standard "square of the Pawn" rule (or is it "square of the King"?). It >>>>>is also very good at detecting that a pawn can win a tempo by checking the >>>>>opponent on its way to promotion. >>>>> >>>>>I do not think it would solve this position though. I am not a good chess >>>>>player, but the position after the Queen exchange seems unclear to me. Black can >>>>>promote first, but White will promote on the next half move. Is it a winning >>>>>advantage? Or I might be missing something. I will try it on TCB when I am back >>>>>home. >>>>> >>>>>Greetings, >>>>>Remi >>>> >>>>Here is a human-like approach: >>>>Apply the rule of the "wandering square". I got it from Awerbachs book about >>>>pawnendings: >>>> >>>>[D]8/8/1k6/8/P2P4/8/8/K7 w - - 0 1 >>>> >>>>In the above diagram the two white pawns are on the corners of a square >>>>(a4-d4-a7-d7). The rule say, that the two pawns are unstoppable by the opposite >>>>king, if their common square has reached the edge of the board. >>>>Since this is not the case, here black has hope to stop the pawns. (He will hold >>>>the draw with 1..Ka5). >>>> >>>>[D]Q3q3/4k3/8/5p2/2p5/8/P6P/4K3 w - - 0 1 >>>>This position is from blass uri. >>>>According to the rule the white pawns are unstoppable. >>>>But the blacks pawns are unstoppable to, after the unavoidable ...f4. >>>>Since we have no dumb advice here, a search is required. It reveals, that black >>>>wins after 1.Qxe8+ but he is only up a tempo. >>>> >>>>Oliver Roese >>> >>> >>>Your rule is interesting, but I have a hard time believing that it holds when >>>the pawns are on their original square. A pawn on its original square can move >>>two squares up (or down), and that should imply a special case for your rule, >>>isn't it? >>> >>> >>> >>> Christophe >> >>The rule is not correct in another case >>[D]8/8/PkP5/8/8/8/8/7K w - - 0 1 >> >>The rule is that white wins but it is a draw. >> >>Uri Good work! I was not aware of this exception. Is there more? > >[D]8/8/8/8/P1k1P3/6p1/7p/7K w - - 0 1 > >Here is another example that I invented when the rule fails. > >The rule is correct here that white pawns are unstoppable but cannot see that >black pawns+king also cannot be stopped. > Sure, but that was not intended. It says not more and not less that the pawns are "unstoppable". >Uri
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