Leela Nets for Human Training and "Style"

[carldaman]

I've hit upon a good approach, but am struggling with how to "measure" the style. Surely this problem must have been addressed in these forums before.

It has been pointed out in the past many times, we've had people like me talking about the style of engines (usually the ones I have the most experience with, like Thinker Inert, Zappa Mexio Dissident Agressor, Toga Chekov, Hiarcs Paderborn 2007, The King (ChessMaster), Pro Deo, Komodo KingHunter, Houdini 6 Contempt 10, Naum 3, and more recently Fizbo and Andscacs), recently I talked at length about how Rybka's playing style changed from version to version and how it compared with her contemporaries. I proposed the Seven Muses Project that would have allowed an engine of interesting playing style to remain competitive against the best, and such a method was automated in chess tool Aiquiri.

But this is the first time I see serious attempts at discussing how to measure style.

One huge problem with it is that, style, as it is, is not always about what moves are played in a position, but about leading the game into positions where piece sacrifices or King attacks, are possible. Sure, once they're possible, 90% of engines will play them, but how many of those would have aimed to this position in the first place? The craziest games by Thinker Inert were those where the engine would reach those positions at all costs, and remember, a good measurer of style would also take into account engines that go into positions that make favorable for the opponent to play sacrifices against them.

Because, if an engine plays always into positions where opponent always exchanges a piece for three pawns against them, it's not the opponent who should be given the style bonuses... Rybka 3 Dynamic was an engine that was aiming towards material imbalances (rook v piece and 2 pawns and such), that's also a clear style.

What I was proposing was to play a few games with an engine that is known already, subjectively, to display some playing style. Say, Fritz 10.1 was an engine known for its famous king attacks. Once you have those games, you give bonuses to engines that play the moves that lead to the positions where the king attack is possible, and so on.

Unfortunately, one thing apparent is that, the stronger an engine gets, the less it displays its "style." Which means style is nothing but suboptimal moves, and what we see in those games is ever worse suboptimal moves, and it's only then that the style triumphs. Match that style against the likes of Stockfish 10 and you'll see how playing without style is stronger. This is the reason Houdini 6 with Contempt 10 is the strongest thing you'll see that displays a very attractive playing style, and yet, Contempt 2 is the default, because the other 8 points just make the engine weaker and weaker.

That's correct - more often than not, it is the suboptimal moves that 'drive' and define the style. Always aiming for the optimal best moves rounds off the 'corners', doing away with style.

However, a real measure of style is still possible among the strongest engines. Take a good look at the games of aggressively super-strong Revenge 1.0 and Velvet 4.1, but also keep in mind that style best surfaces against weaker opponents.