Author: Les Fernandez
Date: 10:44:26 06/10/02
Go up one level in this thread
On June 10, 2002 at 13:15:55, Andrew Williams wrote: >On June 10, 2002 at 11:18:25, Les Fernandez wrote: > >>On June 10, 2002 at 11:01:50, Robert Hyatt wrote: >> >>>On June 10, 2002 at 03:22:55, Andrew Williams wrote: >>> >>>>On June 10, 2002 at 00:18:51, Les Fernandez wrote: >>>> >>>>>On June 10, 2002 at 00:02:39, Robert Hyatt wrote: >>>>> >>>>>>On June 09, 2002 at 23:45:38, Les Fernandez wrote: >>>>>> >>>>>>>I rarely come across strange output using Crafty but this position doesnt seem >>>>>>>to work right. The ce after analysis I think should be -32765 but in fact it is >>>>>>>reporting a "0"??? Either I am dead tired or something is screwy. Would >>>>>>>somebody using Crafty run this epd string? It is a very simple mate and I cant >>>>>>>seem to find the problem. Its probably just late <S>. >>>>>>> >>>>>>>Here is Crafty analysis: >>>>>>> >>>>>>>rnb4k/5r2/2p1p1Q1/pp3pP1/3P4/b2B1KP1/1PPB4/7R b - - acd 1; acn 1; acs 1; ce 0; >>>>>>>pv Rh7; >>>>>>> >>>>>>>The pv appears to be right but the ce value is dead wrong!! >>>>>>> >>>>>>>If you find the same results can someone please explain the nature of this? >>>>>>> >>>>>>>[D]rnb4k/5r2/2p1p1Q1/pp3pP1/3P4/b2B1KP1/1PPB4/7R b - - >>>>>>> >>>>>>> >>>>>>>Thanks >>>>>> >>>>>>Can you describe _exactly_ how you produced that? IE post the epd file >>>>>>you used, etc... >>>>>> >>>>> >>>>>EPD Kit revision date: 1996.04.21 >>>>>unable to open book file [./book.bin]. >>>>>book is disabled >>>>>unable to open book file [./books.bin]. >>>>>search time set to 180.00. >>>>>hash table memory = 48M bytes. >>>>>pawn hash table memory = 10M bytes. >>>>>Crafty 18.9 vs ferret >>>>>kibitz Hello from Crafty v18.9! >>>>>pondering enabled. >>>>>play best book line after search. >>>>>EGTB access enabled >>>>>using tbpath=./TB >>>>>4 piece tablebase files found >>>>>1406kb of RAM used for TB indices and decompression tables >>>>>PFGA: EPD record: 1 >>>>> >>>>>The exact epd string that was in epd.epd was: >>>>> >>>>>rnb4k/5r2/2p1p1Q1/pp3pP1/3P4/b2B1KP1/1PPB4/7R b - - >>>>> >>>>>And the epd.out file was: >>>>> >>>>>rnb4k/5r2/2p1p1Q1/pp3pP1/3P4/b2B1KP1/1PPB4/7R b - - acd 1; acn 1; acs 1; ce 0; >>>>>pv Rh7; >>>>> >>>>> >>>>>The analysis report can be found in my original post here. This one puzzles me >>>>>too Bob but I could not rule out that its late <S>. If you need any additional >>>>>info let me know. >>>>> >>>>>Thanks >>>> >>>>Is this because Black has only one move? In my program, if there's only one move >>>>available *during a game* it only searches to depth 4. For testing epd >>>>positions, it searches normally, even if there is only one move. >>>> >>>>Andrew >>> >>> >>>That might be the reason. With only one move, the epd code in Crafty might >>>not do a search at all, and that would leave the score unchanged from the last >>>epd position perhaps... >> >>Um I am not sure that is what is going on here, let me explain. What I did was >>I took an epd position that reported a mate sequence and then made the pv moves >>and then created all the following epd positions that eventually led to the >>reported mate based on the pv sequence from the first position. Following is >>the results of Crafty which ran the epd's that I created based on the pv line >>from the first position: >> >>rnb4k/5r2/2p1p1Q1/pp3pP1/3P4/b2B1KP1/1PPB4/R7 w - - acd 4; acn 10909; acs 1; ce >>32764; pv Rh1+ Rh7 Rxh7#; >>rnb4k/5r2/2p1p1Q1/pp3pP1/3P4/b2B1KP1/1PPB4/7R b - - acd 1; acn 10909; acs 1; ce >>0; pv Rh7; >>rnb4k/7r/2p1p1Q1/pp3pP1/3P4/b2B1KP1/1PPB4/7R w - - acd 4; acn 7328; acs 1; ce >>32766; pv Rxh7#; >>rnb4k/7R/2p1p1Q1/pp3pP1/3P4/b2B1KP1/1PPB4/8 b - - acd 1; acn 1; acs 1; ce >>-32767; pv; >> >>As you can see the second epd string reports a "0" but the one before it and >>after it are in fact reporting a value. If your thought "With only one move, >>the epd ..... " is correct then why would the last epd position which is the >>actual final move show a ce of -32767 ??? Any other thoughts Bob? >> >>Thanks > >I think the explanation is correct. The only position you listed which has >*exactly* one legal move is the second one, the one where crafty reports 0. The >problem is probably that as a way of saving time in games, many programs just >make the move without searching it (because there's no choice). For the last >position, there are *zero* legal moves. Presumably crafty treats this as a >special case as well (my engine does). If there are no legal moves and the side >to move is in check my engine returns -M00. If it's not in check, it returns >DRAWSCORE. I can't be sure if this applies to crafty too, but I think it's >consistent with the original explanation. Hi Andrew, I see what you are saying but doesn't this pose a problem. ie suppose I have an engine which is doing some type of lookup and sees the ce=0 versuses a mate announcement. If what you are saying is correct does that mean we will never see a ce value = -32765 ??? In the past I know I have gone through millions of epd strings from various sources with the intention of extracting only those epd strings that are end in mate. I look up ce values and only keep those positions that have an abs(ce)>=32000. How do I get around this delemna? Thanks, Les > >Andrew
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