Author: Vasik Rajlich
Date: 08:57:27 03/30/05
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On March 30, 2005 at 04:35:41, Dieter Buerssner wrote: >On March 29, 2005 at 23:37:20, Dann Corbit wrote: > >>That's a funny one, because even the lamest human can see it instantly. > >Dann, I am lamer than the lamest ... >I cannot see it. Also compare the following similar positions: > >[D] 1k6/8/8/8/PPP5/5p1p/8/6K1 w - - > >Here all three white pawns are advanced by two squares -> still won for black. >Now we only advance a and c pawns: > >[D] 1k6/8/8/8/P1P5/5p1p/1P6/6K1 w - - > >And here white wins. White also wins in the next position: > >[D] 1k6/8/8/8/5p1p/8/PPP5/6K1 w - - > >And a serious question: how to see fast, which of those positions is won and >which is lost? Can anybody do it without deep calculation? > >Regards, >Dieter Very cool. My Neuro 1.2 Hz needed approx. 10 min 25 sec to figure this out, but actually it is indeed very simple. What it seems to boil down to is that with the separation of the king and pawns on the queenside, the black king will always win the "tempo war" there and put white into zugzwang. As far as I can see, there is only one type of exception: if white can get two of his pawns to the fifth rank while keeping the third back on his second rank, he can use the flexibility of the second-rank pawn to win the tempo war. That's why the third position is winning: 1. a5 and now 1. .. Ka7 loses to 2. c5 Kb7 3. b4! while 1. .. Kb7 loses to 2. c5 Kb8 3. b3! etc. In the last position, white has a zugzwang-breaking tempo (ie. Kg2) on the kingside which he can use at any time. Vas
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