Author: Robert Hyatt
Date: 17:14:29 08/04/99
Go up one level in this thread
On August 03, 1999 at 16:46:23, Ricardo Gibert wrote: >On August 03, 1999 at 16:16:16, KarinsDad wrote: > >>On August 03, 1999 at 16:00:21, Dann Corbit wrote: >> >>>On August 03, 1999 at 15:33:10, Ricardo Gibert wrote: >>>[snip] >>>>1. Instead of >>>> distance to: mate >>>> >>>>2. Better is single number representing >>>> distance to: mate OR win preseving capture OR win preserving pawn move >>>> (whichever comes soonest) >>>> >>>>The 2nd way you ALWAYS win a winnable position. I find it hard to believe >>>>Nalimov did his EGTB the way you assert (The 1st way). There is nothing I can >>>>think of that would make the 2nd way listed above significant more difficult to >>>>do. There is no good reason, I can think of, for using the 1st way in preference >>>>to the 2nd one. >>>> >>>>I hope this is more clear, otherwise, I give up. >>>How can this be done without the state of the current game information? E.g., I >>>may have gone 49 moves without a capture -- but we clearly can't make the >>>tablebase files 50 times their current size and still have them be practical. >> >>That's the entire point Dann. This does not occur. The program keeps track of >>state information. The file keeps track of just a little more information. The >>file is slightly bigger (i.e. it has 3 sets of information in it which could >>really be dropped down to 2). In other words, the file says: x distance to mate >>here is the next move, y distance to win preserving move. The positions are >>already in that tablebase or in some other tablebase. >> >>The program keeps track of move by rep and 50 move rule. If x > 99 - number of >>moves made so far that apply to 50 move rule, then use the win preserving move >>instead of the mate move. If the mate move leads to a move by rep, then use the >>win preserving move instead (it does not matter whether the win preserving move >>is a capture or a pawn push, just as long as it preserves the win). > >Correcto! I consider it more likely that Bruce and Bob misunderstand the topic, >than Nalimov writing the program the way they suggest. >> no.. just go to my ftp site and download Eugene's code. He really does not fiddle with the 50-move rule or _anything_. If knnn vs k was a mate in 150 (we haven't done the 4 vs 1 so I have no idea) then he reports it as a mate in 150, not a 0 due to the 50 move rule. His code doesn't care about 50 move rules or repetition... it isn't based on that kind of a search. It simply takes mate in 1 positions, finds the moves that take us to predecessor positions and marks those as mated in 2, then the predecessors of those are marked as mate in 2, and so forth, until all positions are marked (excepting those that are illegal/impossible/etc.) >>Any win preserving move by default will automatically reset the 50 move rule. >> >>Eventually, you will get to a state where x <= 99 - number of moves made so far >>that apply to 50 move rule and you win. >> >>KarinsDad :) >> >>[snip]
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