Author: Stephen Ham
Date: 07:08:15 03/02/04
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On March 02, 2004 at 05:19:52, martin fierz wrote: >On March 01, 2004 at 14:40:29, Stephen Ham wrote: > >>On March 01, 2004 at 14:06:15, William Penn wrote: >> >>>Due to a unique bug in Shredder 7 and Shredder 8, its analysis is unreliable. >>>Only the first move can be trusted. Forget the rest! Sometimes it's OK, but >>>often it's garbage, or somewhere in-between. If you want reliable analysis, >>>choose a different engine (not Shredder). >>>WP >> >>Dear William, >> >>I suspect that you misread my post. Yes, in Shredder 7 & 8, only the PV is >>reliable. This is true for some other engines too. For example, I noticed this >>in my matches with Friz 6a and Nimzo 7.32. >>(http://www.correspondencechess.com/campbell/ham/ham.htm). But the a-pawn losing >>move that was second in move-ordering was the PV of the second line of the move >>ordering sequence. >> >>All the best, >>Stephen > >hi stephen > >while i understand what you want to say, you are not saying it correctly. >the PV is the whole line given by shredder. the first move of the PV is always >correct, the entire rest of the PV *can* be garbage but must not. > >so your statemtent "only the PV is reliable" is totally wrong, but i think >that's because you use PV in the sense of "first move of PV" - but since you're >the only one who does this, it will lead to confusion :-) > >cheers > martin Hi Martin, Sorry for my poor communications. My ignorance of chess engine vernacular is showing. Since I'm in finance professionally, PV has a meaning for me which I assumed to be similar to the data output in chess engines. Therefore it may be best to offer an illustration of what I meant. 27 Re1 blah blah blah blah blah uzw... +1.09 16-ply depth What I meant by PV was merely the 1-ply that is represented by 27 Re1, since the remaining thread in S7 and S8 is highly suspect. However, after move ordering through 16-ply depth made 27 Re1 the prime candidate to be played, it then picked 27 a3 to be the next move analyzed in the move ordering sequence. It's my understanding that this move ordering process allocates greater time for analysis of the best candidates. So while S8 still displayed 27 Re1 as the best move, its analysis next switched to 27 a3 blah blah blah blah blah uzw. It's the 27 a3 move that just drops a pawn, so I was shocked to see it placed second in the move ordering sequence. I sincerely hope that this illustration works to make matters clearer. Sorry again for my previous failure to communicate clearly. Thanks to all of you who were willing to educate me, in spite of the frustration that you must have experienced in reading my post. All the very best, Stephen
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