Ziggurat is mostly written by me, but has some public domain code in it. In addition, a great body of work has
preceeded Ziggurat, and I've used many of these ideas. Here I wish to give credit to those whose worked I have used,
and to those I have been inspired from.
Ziggurat uses the ideas from Fruit in the creation of piece-square tables; that is, their automatic construction based
on a smaller set of tunable variables. The comparison of the piece square tables in Fruit and Rybka at https://webspace.utexas.edu/zzw57/rtc/eval/pst.html
has been very enlightening. I took many ideas from this; thanks to Fabien Letouzey for the Fruit program; I do
not know who did the analysis on the above mentioned web page but it was very instructive; thank you. I did not copy
any actual code, but the way Ziggurat creates and uses piece square tables is based on how Fruit does it. Look at the
tuning variables to see how this works.
A very special thanks to the following individuals who have published the code for their chess programs so that others
might learn from their work. Although Ziggurat does not contain source code from these individuals, it was often a great
help to look and see how other world-class programs implemented particularly difficult features:
Thanks to Dan Corbit for the "silent but deadly" suite of test positions.
Special tanks to the following individuals, whose academic papers provided me with long and happy hours of trying to
understand how the best chess programs work: