Author: Komputer Korner
Date: 18:08:52 05/25/05
Go up one level in this thread
On May 24, 2005 at 23:09:09, Komputer Korner wrote: >All the qouted articles in a separate thread do not really explain the tricky >relationship between retro moves, stats, and unplayed transpositions. The trick >is that the retro move stats do not reflect the stats for that retro move. The >stats for the retro move are the total stats for all the option moves at the >previous node where the retro move leads back to. Not only that but the stats >for the retro move are from the opposite colour's point of view in relation to >the colour to move at the previous node. You will notice a weird thing. There >are retro moves for the 1st position. If you click on one of those retro moves, >you will be taken back to a fantasy position before the start of the game with >its own set of retro moves and statistics. Only Chessbase can tell us what this >means. As I have said before, if you click on a retro move that is not in the >game line, you will lose your game score. It is possible to click on retro moves >all the way back to the beginning of the game and to get to a position where it >is black to move for the 1st move. I am sure this has to do with Chessbase >claims about their book's ability to be able to play reverse openings perfectly. > There is a mistake in the Chessbase help manual. In their help >manual it states: " The header displays the total number of games which led to >the current board position." They go on to say that "The N column displays the >number of games in which each move was executed." Only their 2nd statement is >true. In fact the header information displays the number of games in which the >previous move was executed. That is why in most cases the header total N differs >from the column addition of the N. Also don't forget that retro moves are >treated differently with respect to the N. The N represents the total of the >previous header screen when it is referring to a retro move. In fact it is >impossible to tell how many games led to the current board position. You will >notice that unplayed transposition moves can have an N total associated with >them as well. I am sure that this is not the last word on this subject, but what >would be helpful is a separate window that displays all the possible played and >unplayed transposition lines (minus ridiculous fantasy repetition lines) that >could have contributed to the present board position. More on unplayed transposition moves. These are the moves in the tree window that are coloured in grey. You will find stats with these in the ChessBase tree book. You would think that the number N (which means as per the above "The N column displays the number of games in which each move was executed.") would be meaningless if it is an unplayed transposition. Therefore what does this number N mean? Don't forget that we are talking about unplayed moves that if played would lead to a node already in the tree. At least the N total of screen + 1 is always greater than or equal to the N total of the move from screen that lead to screen + 1. When it is greater then there are transposition lines. Notice that it doesn't really matter whether the move is unplayed or not when we are comparing N from 1 screen to the next.
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