Winboard Forum

So I'm a newbie regarding chess engines and opening books, but so far I have reached the point where I can create an opening book using polyglot and tune it in SCID.
The question is: in SCID, how do I know which are black vs white moves? Because SCID lets you add moves and a weight for each move, but how do I know which ones are black?
Also, I don't quite understand what the weight for each move is interpreted by the engines. Any input is appreciated.

Regards,
Gabriel

Nevermind my stupidity, but I finally got it. After you make a move scid will show the available moves and the percentages.
Good god, how simple is that?!

Indeed, this is how it works in WinBoard / XBoard too. The moves and weights shown in the Edit Book window will follow the currently displated position.

The standard way to interpret the weights is to make the probability of playing the moves proportional to their weights. When used as a GUI book in WinBoard / XBoard, the user can further tune this by raising the weights to a power first. This is controlled by the Book Variation in the Common Engine settings dialog. Set that to 0, and ony the move(s) with the largest weight will be played. Set it to 100, and all moves in the book are played equally frequently, irrespective of their weight. The neutral setting is 50. (The power to which the weights are raised is f/(100-f), so for f=50 this is 1, and you have strict proportionality.)

When Polyglot creates the book, the weights are set to the number of half-points scored with the move. Some engines therefor refrain from playing moves with too small an absolute weight. E.g. if the weight is 2, this could be from such a single game that happened to be won, in which case it is not significant, or it was played many times, but almost always lost. In whih case there is even better reason not to play it. Such engines treat a position with 3 moves with weights 5, 4, 2 quite different as when the weights would have been 500, 400 and 200.