[glinscott]

Nearly all the evaluation terms in Stockfish have been extensively tuned. Joona Kiiski used the SPSA[1] algorithm on a lot of them. Others have been hand-tuned using tens of thousands of games per attempt on fishtest [2]. Fishtest actually just recently got support for running SPSA tuning as well.

There is also a strong bias towards simplification, so if an evaluation feature is not proven to be an improvement it will be removed. Over the last few Stockfish versions, the # of lines has actually decreased in each version.

[1] http://en.wikipedia.org/wiki/Simultaneous_perturbation_stoch... [2] http://tests.stockfishchess.org/tests

[icambron]

That's helpful, thanks.