Yes, we have.Rebel wrote:I am sure the SF team have done considerable testing here.
At the end of endless trials with differnt formulas and values we end up in starting with a small window value:
Code: Select all
delta = Value(16);
alpha = RootMoves[PVIdx].prevScore - delta;
beta = RootMoves[PVIdx].prevScore + delta;
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if (bestValue >= beta)
{
beta += delta;
delta += delta / 2;
}
else if (bestValue <= alpha)
{
alpha -= delta;
delta += delta / 2;
}
I want to add that this is the Ippo* formula and I think that very probably it is what is used in _all_ the top engines from Rybka 3 to Houdini. Although we knew the Ippo formula since when sources were published we moved to that only one year later, after having tried all the possible different combinations: some are weaker, some are equivalent ELO wise, but more complex, so this is the simplest formula (we know) that guarantees top performance.
Answering to Uri: I am not interested in tweaking the engine on a sample position. I only use real games to validate a change.