Author: William Penn
Date: 19:59:45 12/06/00
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On December 06, 2000 at 15:57:00, John Merlino wrote: >On December 04, 2000 at 23:27:21, William Penn wrote: > >>CM8000 - an analysis anomaly >> >>This is an analysis after 1.Nf3 Nf6 2.c4 c6 3.Nc3 d5 4.e3 e6 5.d4 Nbd7 6.Qc2 Bd6 >>7.Be2 0-0 8.0-0 e5 9.cxd5 cxd5 10.Nb5 Bb8 11.dxe5 Nxe5 12.Bd2 Bg4. The position >>after 12...Bg4 is as follows: >> >>BR BB -- BQ -- BR BK -- >>BP BP -- -- -- BP BP BP >>-- -- -- -- -- BN -- -- >>-- WN -- BP BN -- -- -- >>-- -- -- -- -- -- BB -- >>-- -- -- -- WP WN -- -- >>WP WP WQ WB WB WP WP WP >>WR -- -- -- -- WR WK -- >> >>This is a known position with 17 example games found in the literature and >>databases. 14 games played 13.Nbd4 which may be considered the book move, 2 >>games played 13.Bb4, and 1 game played 13.Rfc1. Nobody tried 13.Nfd4. Using >>CM8666 Deep (as described previously, analogous to Shep's CM6666 Deep for >>CM6000), analysis yielded the following information in the Thinking Lines >>window: >> >> after 12...Bg4 >>Time Depth Score Positions Moves >>0:28 9 0.37 1M * Bb4 (* rounded off to nearest 1000) >>1:00 10 0.18 3M Bb4 >>2:27 10 0.31 8M Nfd4 >>5:58 11 0.23 19M Nfd4 >>17:31 12 0.14 58M Nfd4 >>23:07 12 0.28 78M Bb4 >>41.43 13 0.12 142M Bb4 >>2:11:00 14 0.13 448M Bb4 >> >>So my CM personality thinks 13.Bb4 is the best move in this position with a >>+0.13 score at 14 ply. It didn't find the book move 13.Nbd4. Why? Well, maybe >>the book move isn't as good. To test this theory, I made the book move. If >>it's not as good, the resulting analysis should give poorer scores (smaller >>positive values) than 13.Bb4. Here's what it shows: >> >> after 12...Bg4 13.Nbd4 >>Time Depth Score Positions Moves >>0.16 9 0.56 1M Nxf3+ >>0.36 10 0.44 2M Nxf3+ >>1:33 11 0.43 5M Nxf3+ >>6:00 12 0.37 20M Nxf3+ >>17:12 13 0.37 59M Nxf3+ >>1:05:00 14 0.29 220M Nxf3+ >> >>Surprisingly 13.Nbd4 gives higher scores than 13.Bb4. I thought that might be >>because the Selective Search was set too high in CM8666 Deep. So I searched >>with smaller Selective Search settings (including a setting of zero, among >>others) but it still couldn't find the book move, 13.Nbd4. >> >>Clearly 13.Nbd4 produces better scores, so why wasn't it found and selected as >>the best move? This is an unexplained anomaly, and I don't know the answer. >>Does anyone? >>WP > >I forwarded your post on to Johan, and here is the gist of his reply: > >-- The GUI supports selective settings of 1 to 12 because those are the >"reasonable" settings. The higher you go past 12, the less useful the data is. >He basically stated the setting of 32 is pretty much a "garbage in/garbage out" >scenario. > >-- The engine does NOT do any checking for "illegal" values in personalities >(meaning values outside of the ranges available in the GUI). Therefore, your >setting of 32 WAS used for CM8666 Deep. > >-- He also stated "This guy is still confused about the score being displayed >for side to move. So the second line is just -0.37 for white, meaning the engine >likes Nbd4 less than Bb4." > >-- Therefore, there is no bug, and this is completely acceptable behavior. > >jm I understood the CM6000 Thinking Lines/Visual Thinking windows OK, but apparently not CM8000. I'm trying, but apparently haven't yet been presented with sufficient information to understand them. There is certainly insufficient (almost no) explanation in the CM8000 release documentation or instructions. The standard protocol is that + scores are good for white. The greater the + score, the better for white. And - scores are good for black. The more negative the number, the better for black. That has nothing to do with the side to move, and is an absolute expression of the current status of the game. Any violation of that standard protocol must be carefully defined, or there is sure to be confusion!? WP
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