Chi-chi Released - Create personalities for Stockfish!

[carldaman]

One other useful feature would be to have asymmetrical piece values, especially for the Queen, so the engine could avoid trading it.

I've been thinking about calling such a setting "Bravery", say, "Queen Bravery" means we're brave enough to trade her without any fear, while low bravery means that if the opponent offers a queen trade, our queen is a coward and runs away to avoid being exchanged

Well, the idea would be to avoid not only unnecessary Q-trades in even games, but also otherwise 'correct' Q-trades when an aggressive Chi-Chi personality is down material (which is not unlikely), to preserve the ability to have counterplay in those situations.

I suppose in those cases the braver thing would be to keep the Queens on the board.
Regardless of what it's called, it would be a form of smart contempt, lacking in SF, and more like what Komodo has.

[Ovyron]

Well, the idea would be to avoid not only unnecessary Q-trades in even games, but also otherwise 'correct' Q-trades when an aggressive Chi-Chi personality is down material (which is not unlikely), to preserve the ability to have counterplay in those situations.

I get you, but I have no idea about how to program that (the queen asymmetry would stay all game, Chi-chi wouldn't know when it's better to trade or when it's better to chicken out - other than what the user sets the value to.)

Hmmm, perhaps some "Smart Contempt" could be implemented (the engine starts the game with the contempt set at the start of the game, then if it's in trouble it's decreased, if it's winning it's increased, etc.)

[carldaman]

Well, the idea would be to avoid not only unnecessary Q-trades in even games, but also otherwise 'correct' Q-trades when an aggressive Chi-Chi personality is down material (which is not unlikely), to preserve the ability to have counterplay in those situations.

I get you, but I have no idea about how to program that (the queen asymmetry would stay all game, Chi-chi wouldn't know when it's better to trade or when it's better to chicken out - other than what the user sets the value to.)

Hmmm, perhaps some "Smart Contempt" could be implemented (the engine starts the game with the contempt set at the start of the game, then if it's in trouble it's decreased, if it's winning it's increased, etc.)

re: piece asymmetry, if the value of the pieces was displayed for both sides, then that could be set by the user; or some sort of +/- differential indicating whether our piece is to be more valuable by a given (centipawn) amount. I think ThothFish may have had something like that.

re: smart contempt - I know Komodo needs a high contempt set for its handicap matches when it's down material from the start, to make sure it avoids trades even if it's somewhat costly to do so, in order to preserve its firepower and ability to fight back. So you probably want a higher smart contempt if down.

What you suggest might apply to a more primitive form of 'draw score', where the engine would want to chicken out with a repetition when it was down by more than its draw score. Smart contempt in Komodo probably integrates this draw score into it as well, or otherwise it could never settle for a draw.

[Rowen]

Hi
Thank you for making this available. I was wondering what the effect of increasing King safety would be, presumably it causes stockfish to look at KIng safety for both sides of the game, hence depending on the 'board position' would either protect its own king more or attack its opponent's king to a greater degree?
So if I increased king safety it would potentially make the program more of a king hunter, (or king defender)?
I am also thinking of the Komodo king safety parameter that seems to make the program more aggressive.
Thanks

[Ovyron]

So if I increased king safety it would potentially make the program more of a king hunter, (or king defender)?

Both.

Before Stockfish 5 it had asymmetrical king safety, so there were two parameters that could be tuned, "Aggressiveness" was for the opponent's king safety, so increasing it would make it a king hunter. "Cowardice" was own king safety, so increasing it would make the engine more defensive of its king.

Shortly after the king safety became symmetrical and Marco Costalba decided to just get rid of the settings, and remove Mobility, Pawn Structure and Passed Pawns settings as well.

Since king safety became symmetrical increasing it in Chi-chi will cause her to become king hunter but assume the opponent is king hunting (so own king is more protected), while decreasing it... huh, it'd make her king hunt less and leave own king unprotected... (so I guess less than 100 king safety currently is pretty useless...)

[Rowen]

So if I increased king safety it would potentially make the program more of a king hunter, (or king defender)?

Both.

Before Stockfish 5 it had asymmetrical king safety, so there were two parameters that could be tuned, "Aggressiveness" was for the opponent's king safety, so increasing it would make it a king hunter. "Cowardice" was own king safety, so increasing it would make the engine more defensive of its king.

Shortly after the king safety became symmetrical and Marco Costalba decided to just get rid of the settings, and remove Mobility, Pawn Structure and Passed Pawns settings as well.

Since king safety became symmetrical increasing it in Chi-chi will cause her to become king hunter but assume the opponent is king hunting (so own king is more protected), while decreasing it... huh, it'd make her king hunt less and leave own king unprotected... (so I guess less than 100 king safety currently is pretty useless...)

Thank you for the reply. I still have many of those old Stockfish versions on my computer, simply to take advantage of those tweakable parameters that were later lost.It is good that people like MikeB and yourself tweak Stockfish versions and release them for people who enjoy playing against them. My ideal would be something like the old chessmaster GUIs but coupled with newer engines, but perhaps there is not any commercial justification for them anymore.Anyway thanks.

[Ovyron]

I still have many of those old Stockfish versions on my computer, simply to take advantage of those tweakable parameters that were later lost.

Yes, now those settings can be brought back

Already working on next version of Chi-chi, what is going to be hard is finding a balance between tweakability and feature creep...