Author: Ricardo Gibert
Date: 18:13:38 08/04/99
Go up one level in this thread
On August 04, 1999 at 20:14:29, Robert Hyatt wrote: >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] You are absolutely correct here.
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