I just released version 3.1 of chess4j, my Java based chess engine. This version is about 100 elo stronger than 3.0. The key differences are:

• The Groovy language is no longer used. Groovy is a fine language for some purposes. chess4j didn’t make heavy use of it but did use it for some I/O type classes, which I wrote about in this post. Unfortunately, it was a constant struggle with my IDE of choice (STS). It constantly balked and complained about the Groovy classes. I had hoped that in time IDE support would improve but in the end I just got tired of constantly messing around with it. On a positive note the chess4j jar file went from 11.5 mb to 4.5 mb.
• Some modest search improvements, worth about 20 elo.
• Added pondering. This means that when it’s the opponent’s turn to move, chess4j is already thinking about its response. If chess4j correctly predicted what the opponent will play, then it is that far ahead in formulating a response (it may even be able to play its move instantly). Seems to be worth about 80 elo.

In my testing, chess4j 3.1 scores 53% against 3.0 in a 1000 game match without pondering, and 64% in a 1600 game match with pondering.

I have my sights set on a parallel search for the 4.0 release, but I think there will be another minor release or two before that to work on search speed optimizations. You can grab the latest and greatest from the project website. Enjoy!