Author: Nathan Thom
Date: 19:12:42 03/07/06
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On March 07, 2006 at 21:34:10, Dann Corbit wrote: > >Opening books hold the frequently played positions near the origin. >If we are talking about some position 50-60 plies down the road, the odds of >hitting it during game play are "astronomical". No, they're "commical" -- and >uneconomical. > >Just the bare positions -- ignoring half-move clock and 3-time repeat are 10 to >the 50th power. So, let's suppose that our intrepid programmer analyzes one >billion positions. The odds in hitting one of them are one in ten to the >forty-first power. Not good. Plus you would have a bit of bloat storing the >positions and a bit of time spent searching for them. > >Now, let's suppose that we bypass all these objections and say "What the heck, >let's do it anyway!" > >Well, when we look at memory, we will see (one billion * hash element size) >bytes of memory consumed. A very small hash entry would consume 16 bytes but >we'll say he's clever and stores only 8 bytes. That would be 8 gigs of ram. > >"Well..." (you may retort) "perhaps they are loaded on demand." > >I suppose that a page fault for every new position would slow down the program >so much that we would see 50-100 NPS at best. While Rybka may be a slow >searcher (let's not start that debate) it's certainly not that slow. > >I suppose we're just going to have to admit that V.R. is a clever guy, and that >he hasn't stored the middle game in the computer's data segments. What about only considering parts of the board (<64 squares) or only specific pieces. e.g. only consider rooks+kings and have a pre-generated table of the most common situations and best move? Sure, the other pieces which have been ignored could make the move ridiculous or illegal but i wonder what kind of success rate this would give?
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