FRC always pumps up the rating of the strongest engine, especially if it plays with contempt also against weaker opponents, as FRC is in general more complex than normal chess and king safety has higher bearing on the results.
Also, FRC, as a less symmetric chess variant, necessarily pushes up the winning rate, and that again always favours the strongest engine.
Houdini 6 tactical is now best in all my testsuite (tactical and endgame). Only Houdini 1.5 has been even better . But for matesolving SF matefinder 2016 (december) is still unbeaten! Some figures: 150 difficult mates from Chest database. Matefinder solves 105 in minute level - Houdini 87.
Not too hard, since Zipproth has not published the format (to my knowledge). It could be discerned by examining Brainfish source code, but other engine authors should not be expected to do this.
Then again, Robert might just as well make his own backsolved book with Houdini. It's something I would consider doing myself, but the Houdini license apparently does not allow it.
Houdini wrote:Why? Our philosophy has always been that book management (in particular the probabilities of choosing between the different moves available in the opening book) is done by the GUI that runs the engine.
Each GUI has its own, different book format; if you’re using Arena, your book will be in the Arena ABK format; if you're using Fritz/ChessBase you'll be using ctg format book, etc.
To use an engine you'll eventually need a GUI; the GUI might then as well make the book move selection.
As an outsider to computer chess this always struck me as a strange architectural decision. If GUI handles book, engine cannot use its evaluations when searching. As Brainfish proved, engine strength can be substantially increased with only ~ 50 MB stored evals. Yet engine authors happily support ~ 1 TB tablebases that improve playing strength far less.
Based on Regan's guestimate of perfect play at 3600 Elo, we are within 5 years of weakly solving game. Idea of opening "book" as something created with human input is an anachronism. Absolute truth of many openings is already known, and indeed already found in Cerebellum.
Many other strange ideas in computer chess. Such as running engines on one's local machine...