Author: Ratko V Tomic
Date: 23:26:12 07/27/00
Go up one level in this thread
> Why 5-6 bits per ply? Just enough to represent an > appoximate evaluation of the position? No, not the evaluation but how many bits are needed to specify the ply. The evaluation of a move strength is implied in the move choice itself. In principle a human evaluation of a single ply could have vast amounts of descriptions about the strength and weaknesses of a move (or, say, about the time used or the player's behaviour during the game). But all such analysis of a strength of the move follows from the specification of the move. This kind extra information is external to the game (it comes from sources other than the game itself, and varies in quantity depending on the source). In other words the quantity of information contained in the game itself (and thus extractible solely from the game) equals the minimum number of bits needed to specify (reconstruct) uniquely that game. Anything else comes from other sources. Your observation in fact highlights that this additional/contextual information, external to the game (where the game is placed in the context of the existent chess theory), can also be useful in judging the strength of the players, thus adding further to the effectivness of the expert extractor compared to the rating calculator. The crude estimate of 5 bits/ply assumes thus 32 choices available per ply, all equally likely (which maximizes the entropy production per ply). In a real game that is obviously not the case (i.e. different choices have different probabilities, unless the set of players includes random players), thus the entropy production is lower than the 5 bits per ply, perhaps around 2-3 bits on a more realistic set of players.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.