Bounds

[dav1312]

It would be better if the alpha/beta bounds were the score difference to the current position, not to the starting position

[robertnurnberg]

Does #4 address your concerns? @dav1312

Note that with e.g. python chessgraph.py --salpha 5 --sbeta 5 --position FEN you will now get a reasonable graph for any FEN, without having to know the precise evaluation of the position.

[dav1312]

I can't test right now but it seems to do what I wanted

[robertnurnberg]

Great. Once you have tested it, feel free to close the issue. :)

[dav1312]

Now that I was able to test it it doesn't seem to be doing what I wanted.
Basically, due to chessdb's eval decay, every few ply there is a "random" 1cp change in the position eval that can go up or down.

For example:

Move	Eval
g4	-1.20
d5	-1.20
e3	-1.20
Nc6	-1.20
d4	-1.20
e5	-1.21
Nc3	-1.21
Be6	-1.22

In my idea, a bound of +-1 would not stop at the end, because the eval of the previous move was within those bounds.
In the current implementation, a 1cp bound will never reach the last move.

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Note that this is not just about the eval decay since my idea extends to inaccurate moves too for example.
If I ask for 10cp bounds in a 0cp starting position, the current implementation limits the amount of moves to only the ones that are +-10cp, but my idea would allow a series of innacuracies as long as they are within those bounds like 0 -> 10 -> 20 -> 30 -> 40 -> 30