v2.2.0

Releasing Horowitz v2.2.0.

Changes mainly involved minor improvements in late move reductions and quiet moves ordering in search. A very basic hash table was also implemented for storing pawn structures in evaluation.

Score of horowitz-new vs horowitz-old: 34 - 19 - 47 [0.575]
...      horowitz-new playing White: 18 - 10 - 22  [0.580] 50
...      horowitz-new playing Black: 16 - 9 - 25  [0.570] 50
...      White vs Black: 27 - 26 - 47  [0.505] 100
Elo difference: 52.5 +/- 49.9, LOS: 98.0 %, DrawRatio: 47.0 %

v2.1.0

Releasing Horowitz v2.1.0.

This version essentially consists of a simpler evaluation function and a much faster search function. This has produced a reasonable gain in playing strength. Evaluation now uses PSQT's + Material (both now incrementally updated) and mop-up evaluation for converting late endgame positions. Other changes include various bug fixes.

Here are the final scores of v2.1.0 vs v2.0.0 in a match consisting of 100 games (TC 40/10s + 0.1):

Score of horowitz-new vs horowitz-old: 66 - 17 - 17 [0.745]
...      horowitz-new playing White: 39 - 8 - 3  [0.810] 50
...      horowitz-new playing Black: 27 - 9 - 14  [0.680] 50
...      White vs Black: 48 - 35 - 17  [0.565] 100
Elo difference: 186.2 +/- 70.4, LOS: 100.0 %, DrawRatio: 17.0 %
100 of 100 games finished. TC: 40/10s + 0.1

Horowitz v2.0

Second release of Horowitz.

The engine has been completely rewritten in C++. New features include delta pruning, faster move generation (pin and check masks) and better evaluation (doubled pawn penalties, mop-up eval, open files and very basic king safety). I don't expect it to be significantly stronger than version 1.0 as I have not tested them thoroughly.

Horowitz v1.0

The first release of Horowitz.