Monday, December 14, 2015

Oh, very clever, Worf. Eat any good books lately?

Problematic position from the two knights defence - the book lists two correct moves again

As the YAT tournament revealed some problems with the old opening books of iCE I put opening books at the top of my todo list. The code is very old, more than 3 years and goes back to version 0.3. iCE was here available only as 32 bit program with an estimated strength of 2460 ELO.

So it was time to modernize that anyway.

I decided not only to fix the illegal moves (related to changes in en passent handling between version 0.3 and 2.0) but to rebuild the books. I also want to tailor the books towards iCE's playing style.

What does this mean?

A human chess player will play openings that lead to positions that he is comfortable with, like positions full of tactics if he is skilled tactical player or quiet ones if he is not. He will avoid openings were he struggles. The books of iCE don't handle that. The probability that a move is selected from the list of possible moves only depends on the probability that with this move a game played by strong engines later was won. It ignores the playing style of iCE as this information currently is just not present.

I plan to extend the data structure of the book building framework to store move performance data of iCE and use this performance data in the book building process.

I don't expect a huge impact on playing strength but it seems like the proper way to do it and is much more interesting than tuning values to death.
And as holidays are coming I will find some time to do it, hopefully.