Author: Bruce Moreland
Date: 10:07:19 11/15/00
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On November 15, 2000 at 05:06:44, Jason Williamson wrote: >On November 15, 2000 at 04:14:55, Bruce Moreland wrote: > >>On November 15, 2000 at 02:04:12, Jason Williamson wrote: >> >>>In the 2nd game I ran with xboard engines under CM8000 a serious >>>misinterpratation of the 50 move rule was uncovered. >>> >>>The ending in particular was a drawn Rook and Bishop verus Bishop ending. After >>>the 50th move with the move of a pawn or capture of a piece by white, black >>>(Zchess 2.22) claimed the draw and according to its log quit. >>> >>>The problem is, the CM8000 gui doesn't know how to do the 50 move rule. What it >>>seems to think is that the draw is after the 50th move SET, ie white AND black, >>>which is clearly wrong. To test this theory out, I moved knights and rooks >>>around from the starting position for 50 moves. Since no pawn was moved, nor >>>anything was captured, the 50 move that this happens would be white 50 (0+50=50) >>>but the GUI only claims the draw after the black 50th move. >>> >>>Anyway, this would basicly break any and all winboard engines that are coded >>>correctly and this bug would be a frequent vistor to engine vs engine matches. >>> >>>So, how long until the patch. :) >>> >>>Cheers. >>> >>>JW >> >>The rule is that 50 moves must have been made *by each side*, so the CM gui is >>correct. >> >>Imagine if we had a one-move rule instead of a fifty-move rule. White could not >>claim that 1. Nf3 is drawn by this rule, but after 1. Nf3, black could claim >>that 1. ... Nf6 does in fact draw by this rule. >> >>If 1. e4, black cannot claim that 1. ... Nf6 forces a draw by this rule, but >>after 1. e4 Nf6, white can claim that 2. Nc3 forces a draw. >> >>bruce > >Hmm, it seems you are correct. :) (Looked up the rule at the CFC homepage to >double check). The problem with this situation is this: White's 71 move was a >capture. Both Crafty and ZChess's logs state draw on move white 121. Thus, it >appears that both Crafty and ZChess interupt this rule wrong. As you pointed >out, black must play 50 moves as well, and that means black must play its 121st >move. > >Interesting. > >JW I doubt that Crafty got it wrong, because Crafty has to play according to this rule on ICC. White's 71st move was a capture. That means that by using the one-move rule, if black makes a reversible move, and makes a reversible move, a draw can be claimed along with white's 72nd move. 72 - 71 is 1. So to do the 50-move rule we should get 71 + 50 = 121. White's 121st move should be accompanied by a draw claim. This seems in line with what you just said. Are you saying that a draw would be claimed only after black's 121st? That's wrong. bruce
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