Rebelfish is intended to enrich the Stockfish engine with typical Rebel | ProDeo features such as in ProDeo 2.9 and at the same time (for the fun part) allow ProDeo in reverse to profit from Stockfish strength via an old REBEL 10 trick notable from the previous century. But first things first. At program start the (below) freeware text program Editpad will pop-up and displlay all sorts of information via its tabulators.
As with the (old 1999) EOC approach, see section EOC usage during calculating the engine applies a bonus based on the results of the EOC database to guide the engine but now -- 20 years later -- the database is replaced by Stockfish running in the background. Same technique, different database and not limited to the opening phase but always available. And the results are spectacular. Depending on the time control 250-400 elo.
Rebelfish is controlled by the configuration file Rebelfish.ini visible in the corresponding Editpad tabulator.
[ProDeo engine parameters]
[Score Margin = 0.25]
The applied bonus for Stockfish best move. The default setting of 0.25 already gave ProDeo a boast of 270 elo in self-play. Increasing the value to 0.50 the elo gain went up to 386.
To avoid a further increase of elo (and further similarity) a value > 0.50 will result in a complete takeover by Stockfish recognizable by adding 100 to depth on your screen so there can be no mistake which engine is in charge.
On the other hand a value of 0.00 will force ProDeo to play without the help of Stockfish.
How much equal is Rebelfish to Stockfish 10? Answer, it depends on the setting of [Score Margin = 0.25]
And Similarity tester from Komodo programmer Don Daily is the tool to measure that. And so we tested the following score margins: 0.50 (the maximum) | 0.25 (the default setting) | 0.20 | 0.15 | 0.10 | 0.05 and finally 0.00 meaning the influence of Stockfish is nihil. The results:
Stockfish 10 Similarity
Playing as ProDeo 2.9.
The default setting.
The maximum setting.
For a more complete overview including some background info about Similarity Tester check out this text file.
Stockfish is the work of T. Romstad, M. Costalba, J. Kiiski, G. Linscott.