how to know when to start the endgame evaluation??

[pimidrez]

hello everyone, my question is simple, how to know when to start the endgame evaluation?? like when to start using the pst for endgames, etc..
counting how much pieces are on the board? or wich pieces on the board?

is there any document for this??

[H.G.Muller]

Most engines make a gradual transition nowadays. E.g. Fruit interpolates the opening and end-game PST based on a game-phase indicator minors+2*rooks+4*queens. For things that cannot be interpolated, e.g. switching off the check extension, I use the criterion that the opponent must not have more than a Queen. (But perhaps a limit of Q+minor would also be OK.)

[pimidrez]

Thanks muller! but I dont understand when you say "minors+2*rooks+4*queens" ... its a formula? can you explain it a little bit?

thanks!!

[H.G.Muller]

Yes, it is the piece names stand for the number of pieces of that type. So basically Rooks count for 2, and Queens for 4. When the formula gives zero, you are in the latest possible end game (no pieces left, just Pawns) when it is 24 (or 12, when you count perside), you are in the opening phase (for FIDE Chess).