Usage

Setup

To setup a simple tune, you need the following directory structure:

   .
   ├── simple_tune.json
   ├── engine1
   ├── engine2
   └── openings.pgn

engine1 and engine2 are the executables for two chess engines. The convention of this library is that the first engine is the one that will be tuned. openings.pgn should contain a suitable set of openings. Finally, simple_tune.json is the most important file and contains the actual tuning configuration. Here we use a very simple configuration:

   {
       "engines": [
           {
               "command": "engine1",
               "fixed_parameters": {
                   "Threads": 2
               }
           },
           {
               "command": "engine2",
               "fixed_parameters": {
                   "Threads": 4
               }
           }
       ],
       "parameter_ranges": {
           "CPuct": "Real(0.0, 10.0)"
       },
       "engine1_tc": "1+0.1",
       "engine2_tc": "1+0.1",
       "rounds": 20,
       "opening_file": "openings.pgn"
   }

The engines are given as a list. The command field should contain the path to the executable of the corresponding engine. fixed_parameters is optional and can contain fixed UCI parameters for each engine. These will not be changed by the tuner. parameter_ranges contains the actual UCI parameters to be optimized and their ranges. Here we optimize a parameter called CPuct. We tell the tuner that the parameter can assume real values from 0 to 10. Another common parameter type is Integer.

An important part of the tuning process is the time control. The tuner uses cutechess-cli to run matches. Here we use a time control of 1s + 0.1s increment for both engines. Depending on the hardware used, it may be necessary to calibrate the correct ratio of time controls such that both engines are of equal strength. The number of rounds specify how many rounds the tuner should run to evaluate one parameter configuration. Each round consists of two games (one random opening played from both sides). The opening_file field contains the path to an epd or pgn file and will be used by cutechess-cli to select random openings for the matches.

Run the tuner

Navigate to the folder and then run:

   tune local -c simple_tune.json